| Message ID | 1365419265-21238-1-git-send-email-vikas.sajjan@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 8 April 2013 16:37, Vikas Sajjan <vikas.sajjan@linaro.org> wrote: > While migrating to common clock framework (CCF), I found that the FIMD clocks > were pulled down by the CCF. > If CCF finds any clock(s) which has NOT been claimed by any of the > drivers, then such clock(s) are PULLed low by CCF. > > Calling clk_prepare() for FIMD clocks fixes the issue. > > This patch also replaces clk_disable() with clk_unprepare() during exit, since > clk_prepare() is called in fimd_probe(). I asked you about fixing your commit log too.. It still looks incorrect to me. This patch doesn't have anything to do with CCF pulling clocks down, but calling clk_prepare() before clk_enable() is must now.. that's it.. nothing more. > Signed-off-by: Vikas Sajjan <vikas.sajjan@linaro.org> > --- > Changes since v3: > - added clk_prepare() in fimd_probe() and clk_unprepare() in fimd_remove() > as suggested by Viresh Kumar <viresh.kumar@linaro.org> > Changes since v2: > - moved clk_prepare_enable() and clk_disable_unprepare() from > fimd_probe() to fimd_clock() as suggested by Inki Dae <inki.dae@samsung.com> > Changes since v1: > - added error checking for clk_prepare_enable() and also replaced > clk_disable() with clk_disable_unprepare() during exit. > --- > drivers/gpu/drm/exynos/exynos_drm_fimd.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c > index 9537761..aa22370 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c > @@ -934,6 +934,16 @@ static int fimd_probe(struct platform_device *pdev) > return ret; > } > > + ret = clk_prepare(ctx->bus_clk); > + if (ret < 0) > + return ret; > + > + ret = clk_prepare(ctx->lcd_clk); > + if (ret < 0) { > + clk_unprepare(ctx->bus_clk); > + return ret; > + } > + > ctx->vidcon0 = pdata->vidcon0; > ctx->vidcon1 = pdata->vidcon1; > ctx->default_win = pdata->default_win; > @@ -981,8 +991,8 @@ static int fimd_remove(struct platform_device *pdev) > if (ctx->suspended) > goto out; > > - clk_disable(ctx->lcd_clk); > - clk_disable(ctx->bus_clk); > + clk_unprepare(ctx->lcd_clk); > + clk_unprepare(ctx->bus_clk); This looks wrong again.. You still need to call clk_disable() to make clk enabled count zero... -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 20 April 2013 20:56, Inki Dae <inki.dae@samsung.com> wrote: > Sorry for being late. I think clk_prepare/unprepare are nothing to do yet in > case of Exynos but those might be used for in the future so your patch looks > good to me as is. > > Applied. :) And you think the comments i gave were incorrect then? Why? -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi, On Monday 08 of April 2013 16:41:54 Viresh Kumar wrote: > On 8 April 2013 16:37, Vikas Sajjan <vikas.sajjan@linaro.org> wrote: > > While migrating to common clock framework (CCF), I found that the FIMD > > clocks were pulled down by the CCF. > > If CCF finds any clock(s) which has NOT been claimed by any of the > > drivers, then such clock(s) are PULLed low by CCF. > > > > Calling clk_prepare() for FIMD clocks fixes the issue. > > > > This patch also replaces clk_disable() with clk_unprepare() during > > exit, since clk_prepare() is called in fimd_probe(). > > I asked you about fixing your commit log too.. It still looks incorrect > to me. > > This patch doesn't have anything to do with CCF pulling clocks down, but > calling clk_prepare() before clk_enable() is must now.. that's it.. > nothing more. > I fully agree. The message should be something like: Common Clock Framework introduced the need to prepare clocks before enabling them, otherwise clk_enable() fails. This patch adds clk_prepare calls to the driver. and that's all. What you are observing as "CCF pulling clocks down" is the fact that clk_enable() fails if the clock is not prepared and so the clock is not enabled in result. Another thing is that CCF is not pulling anything down. GPIO pins can be pulled down (or up or not pulled), but clocks can be masked, gated or simply disabled - this does not imply their signal level. > > Signed-off-by: Vikas Sajjan <vikas.sajjan@linaro.org> > > --- > > > > Changes since v3: > > - added clk_prepare() in fimd_probe() and clk_unprepare() in > > fimd_remove()> > > as suggested by Viresh Kumar <viresh.kumar@linaro.org> > > > > Changes since v2: > > - moved clk_prepare_enable() and clk_disable_unprepare() from > > fimd_probe() to fimd_clock() as suggested by Inki Dae > > <inki.dae@samsung.com>> > > Changes since v1: > > - added error checking for clk_prepare_enable() and also > > replaced > > clk_disable() with clk_disable_unprepare() during exit. > > > > --- > > > > drivers/gpu/drm/exynos/exynos_drm_fimd.c | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > b/drivers/gpu/drm/exynos/exynos_drm_fimd.c index 9537761..aa22370 > > 100644 > > --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > @@ -934,6 +934,16 @@ static int fimd_probe(struct platform_device > > *pdev)> > > return ret; > > > > } > > > > + ret = clk_prepare(ctx->bus_clk); > > + if (ret < 0) > > + return ret; > > + > > + ret = clk_prepare(ctx->lcd_clk); > > + if (ret < 0) { > > + clk_unprepare(ctx->bus_clk); > > + return ret; > > + } > > + Why not just simply use clk_prepare_enable() instead of all calls to clk_enable() in the driver? Same goes for s/clk_disable/clk_disable_unprepare/ . > > > > ctx->vidcon0 = pdata->vidcon0; > > ctx->vidcon1 = pdata->vidcon1; > > ctx->default_win = pdata->default_win; > > > > @@ -981,8 +991,8 @@ static int fimd_remove(struct platform_device > > *pdev)> > > if (ctx->suspended) > > > > goto out; > > > > - clk_disable(ctx->lcd_clk); > > - clk_disable(ctx->bus_clk); > > + clk_unprepare(ctx->lcd_clk); > > + clk_unprepare(ctx->bus_clk); > > This looks wrong again.. You still need to call clk_disable() to make > clk enabled > count zero... Viresh is right again here. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sunday 21 of April 2013 13:23:10 Viresh Kumar wrote: > On 20 April 2013 20:56, Inki Dae <inki.dae@samsung.com> wrote: > > Sorry for being late. I think clk_prepare/unprepare are nothing to do > > yet in case of Exynos but those might be used for in the future so > > your patch looks good to me as is. > > > > Applied. :) > Hmm. Now, after searching for this thread in dri-devel archives, I'm wondering why I haven't received some of messages from this thread through linux-samsung-soc mailing list... I believe linux-samsung-soc list exists to collect all threads related to Samsung SoCs for people that don't want to subscribe to lists like dri- devel, on which there is a lot of threads irrelevant to them, with the risk of missing the important ones. Please always make sure that any discussion about Samsung SoCs (patches in particular) is going through linux-samsung-soc as well. Thanks in advance. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Inki, On Sunday 21 of April 2013 23:05:45 Inki Dae wrote: > 2013/4/21 Tomasz Figa <tomasz.figa@gmail.com> > > > On Sunday 21 of April 2013 13:23:10 Viresh Kumar wrote: > > > On 20 April 2013 20:56, Inki Dae <inki.dae@samsung.com> wrote: > > > > Sorry for being late. I think clk_prepare/unprepare are nothing to > > > > do > > > > yet in case of Exynos but those might be used for in the future so > > > > your patch looks good to me as is. > > > > > > > > Applied. :) > > > > Hmm. Now, after searching for this thread in dri-devel archives, I'm > > wondering why I haven't received some of messages from this thread > > through linux-samsung-soc mailing list... > > > > I believe linux-samsung-soc list exists to collect all threads related > > to Samsung SoCs for people that don't want to subscribe to lists like > > dri- devel, on which there is a lot of threads irrelevant to them, > > with the risk of missing the important ones. > > > > Please always make sure that any discussion about Samsung SoCs > > (patches in particular) is going through linux-samsung-soc as well. > > Thanks for your advice. As you said, some people might not want to > subscribe to some mainling lists they don't want. And I think that the > main mailing list on this patch is dri-devel so you must receive this > email thread if you subscribed to the dri-devel. I agree that dri-devel is the target mailing list for DRM patches, but AFAIK all threads related to Samsung SoCs should be sent to linux-samsung- soc as well. For example, I don't subscribe dri-devel, but I do linux-samsung-soc, because all I want to follow is all the works related to Samsung SoCs. Remaining threads on dri-devel are outside of my competencies. > Anyway it would be > best to share this all mailing lists included in this email thread but > if so, I have no doubt to receive email bumb. :( Hmm, you don't have to subscribe to a mailing list to post to it. Actually I'm wondering if the fact that your previous messages did not get to the linux-samsung-soc list was not caused by presence of HTML part in your messages, which is strongly discouraged on all mailing lists and actually blocked on vger.kernel.org where linux-samsung-soc is hosted. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Inki, On Sunday 21 of April 2013 22:36:08 Inki Dae wrote: > 2013/4/21 Tomasz Figa <tomasz.figa@gmail.com> > > > Hi, > > > > On Monday 08 of April 2013 16:41:54 Viresh Kumar wrote: > > > On 8 April 2013 16:37, Vikas Sajjan <vikas.sajjan@linaro.org> wrote: > > > > While migrating to common clock framework (CCF), I found that the > > > > FIMD > > > > clocks were pulled down by the CCF. > > > > If CCF finds any clock(s) which has NOT been claimed by any of the > > > > drivers, then such clock(s) are PULLed low by CCF. > > > > > > > > Calling clk_prepare() for FIMD clocks fixes the issue. > > > > > > > > This patch also replaces clk_disable() with clk_unprepare() during > > > > exit, since clk_prepare() is called in fimd_probe(). > > > > > > I asked you about fixing your commit log too.. It still looks > > > incorrect > > > to me. > > > > > > This patch doesn't have anything to do with CCF pulling clocks down, > > > but calling clk_prepare() before clk_enable() is must now.. that's > > > it.. nothing more. > > > > I fully agree. > > > > The message should be something like: > > > > Common Clock Framework introduced the need to prepare clocks before > > enabling them, otherwise clk_enable() fails. This patch adds > > clk_prepare calls to the driver. > > > > and that's all. > > > > What you are observing as "CCF pulling clocks down" is the fact that > > clk_enable() fails if the clock is not prepared and so the clock is > > not > > enabled in result. > > > > Another thing is that CCF is not pulling anything down. GPIO pins can > > be pulled down (or up or not pulled), but clocks can be masked, gated > > or simply disabled - this does not imply their signal level. > > > > > > Signed-off-by: Vikas Sajjan <vikas.sajjan@linaro.org> > > > > --- > > > > > > > > Changes since v3: > > > > - added clk_prepare() in fimd_probe() and clk_unprepare() > > > > in > > > > fimd_remove()> > > > > > > > > as suggested by Viresh Kumar <viresh.kumar@linaro.org> > > > > > > > > Changes since v2: > > > > - moved clk_prepare_enable() and clk_disable_unprepare() > > > > from > > > > fimd_probe() to fimd_clock() as suggested by Inki Dae > > > > <inki.dae@samsung.com>> > > > > > > > > Changes since v1: > > > > - added error checking for clk_prepare_enable() and also > > > > replaced > > > > clk_disable() with clk_disable_unprepare() during exit. > > > > > > > > --- > > > > > > > > drivers/gpu/drm/exynos/exynos_drm_fimd.c | 14 ++++++++++++-- > > > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > > > b/drivers/gpu/drm/exynos/exynos_drm_fimd.c index 9537761..aa22370 > > > > 100644 > > > > --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > > > +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > > > @@ -934,6 +934,16 @@ static int fimd_probe(struct platform_device > > > > *pdev)> > > > > > > > > return ret; > > > > > > > > } > > > > > > > > + ret = clk_prepare(ctx->bus_clk); > > > > + if (ret < 0) > > > > + return ret; > > > > + > > > > + ret = clk_prepare(ctx->lcd_clk); > > > > + if (ret < 0) { > > > > + clk_unprepare(ctx->bus_clk); > > > > + return ret; > > > > + } > > > > + > > > > Why not just simply use clk_prepare_enable() instead of all calls to > > clk_enable() in the driver? > > > > Same goes for s/clk_disable/clk_disable_unprepare/ . > > I agree with you. Using clk_prepare_enable() is more clear. Actually I > had already commented on this. Please see the patch v2. But this way > also looks good to me. Well, both versions are technically correct and will have the same effect for Exynos SoC clocks, since only enable/disable ops change hardware state. However if we look at general meaning of those generic ops, the clock will remain prepared for all the time the driver is loaded, even if the device is runtime suspended. Again on Exynos SoCs this won't have any effect, but I think we should respect general Common Clock Framework semantics anyway. > > > > ctx->vidcon0 = pdata->vidcon0; > > > > ctx->vidcon1 = pdata->vidcon1; > > > > ctx->default_win = pdata->default_win; > > > > > > > > @@ -981,8 +991,8 @@ static int fimd_remove(struct platform_device > > > > *pdev)> > > > > > > > > if (ctx->suspended) > > > > > > > > goto out; > > > > > > > > - clk_disable(ctx->lcd_clk); > > > > - clk_disable(ctx->bus_clk); > > > > + clk_unprepare(ctx->lcd_clk); > > > > + clk_unprepare(ctx->bus_clk); > > > > > > This looks wrong again.. You still need to call clk_disable() to > > > make > > > clk enabled > > > count zero... > > > > Viresh is right again here. > > Ok, you two guys say together this looks wrong so I'd like to take more > checking. I thought that clk->clk_enable is 1 at here and it would be 0 > by pm_runtimg_put_sync(). Is there any my missing point? You're reasoning is correct, but only assuming that runtime PM is enabled. When it is disabled, pm_runtime_put_sync() is a no-op. Well, after digging into the exynos_drm_fimd driver a bit more, it seems like its power management code needs a serious rework, because I was able to find more problems: 1) fimd_activate() does not get called at all if CONFIG_PM_RUNTIME is not enabled (except in system-wide suspend callbacks, but this is irrelevant to this point) - this means that the hardware is not properly initialized without CONFIG_PM_RUNTIME - at least clocks does not get enabled. 2) pm_runtime_set_suspended() can be used only when runtime PM is disabled for the device (i.e. by calling pm_runtime_disable() or not calling pm_runtime_enable() at all) - when runtime PM is enabled it is basically a no-op returning -EAGAIN error. So here's my proposed solution: 1) call fimd_activate() and pm_runtime_set_active() explicitly in fimd_probe(), before calling pm_runtime_enable(): mutex_init(&ctx->lock); platform_set_drvdata(pdev, ctx); + + fimd_activate(ctx, true); + pm_runtime_set_active(dev); pm_runtime_enable(dev); pm_runtime_get_sync(dev); This would power up the device even if CONFIG_PM_RUNTIME is not enabled. Note that pm_runtime_get_sync() after marking the device as active with pm_runtime_set_active() won't result in calling fimd_runtime_resume(), because the device is considered already resumed. 2) in fimd_remove(): + pm_runtime_disable(dev); + if (ctx->suspended) - goto out; + return 0; - clk_disable(ctx->lcd_clk); - clk_disable(ctx->bus_clk); + fimd_activate(ctx, false); + pm_runtime_put_noidle(dev); pm_runtime_set_suspended(dev); - pm_runtime_put_sync(dev); - -out: - pm_runtime_disable(dev); First, pm_runtime_disable() will prevent any further runtime PM operations that could change ctx->suspended state. Then, if ctx->suspended is true, there is no need to suspend anything and we can leave. Otherwise, we power down the hardware manually - which will work with both CONFIG_PM_RUNTIME enabled and disabled, and then mark the hardware as suspended and free remaining reference in runtime PM core. Note that pm_runtime_put_noidle just decreases the reference counter and nothing else. 3) after those two changes, all that remains is to fix compliance with Common Clock Framework, in other words: s/clk_enable/clk_prepare_enable/ and s/clk_disable/clk_disable_unprepare/ Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 21 April 2013 20:13, Tomasz Figa <tomasz.figa@gmail.com> wrote: > 3) after those two changes, all that remains is to fix compliance with > Common Clock Framework, in other words: > > s/clk_enable/clk_prepare_enable/ > > and > > s/clk_disable/clk_disable_unprepare/ We don't have to call clk_{un}prepare() everytime for your platform as you aren't doing anything in it. So just call them once at probe/remove and call clk_enable/disable everywhere else. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sunday 21 of April 2013 22:36:08 Inki Dae wrote: > > > 2013/4/21 Tomasz Figa <tomasz.figa@gmail.com> > > > > > > > Hi, > > > > > > > > On Monday 08 of April 2013 16:41:54 Viresh Kumar wrote: > > > > > On 8 April 2013 16:37, Vikas Sajjan <vikas.sajjan@linaro.org> wrote: > > > > > > While migrating to common clock framework (CCF), I found that the > > > > > > FIMD > > > > > > clocks were pulled down by the CCF. > > > > > > If CCF finds any clock(s) which has NOT been claimed by any of the > > > > > > drivers, then such clock(s) are PULLed low by CCF. > > > > > > > > > > > > Calling clk_prepare() for FIMD clocks fixes the issue. > > > > > > > > > > > > This patch also replaces clk_disable() with clk_unprepare() during > > > > > > exit, since clk_prepare() is called in fimd_probe(). > > > > > > > > > > I asked you about fixing your commit log too.. It still looks > > > > > incorrect > > > > > to me. > > > > > > > > > > This patch doesn't have anything to do with CCF pulling clocks down, > > > > > but calling clk_prepare() before clk_enable() is must now.. that's > > > > > it.. nothing more. > > > > > > > > I fully agree. > > > > > > > > The message should be something like: > > > > > > > > Common Clock Framework introduced the need to prepare clocks before > > > > enabling them, otherwise clk_enable() fails. This patch adds > > > > clk_prepare calls to the driver. > > > > > > > > and that's all. > > > > > > > > What you are observing as "CCF pulling clocks down" is the fact that > > > > clk_enable() fails if the clock is not prepared and so the clock is > > > > not > > > > enabled in result. > > > > > > > > Another thing is that CCF is not pulling anything down. GPIO pins can > > > > be pulled down (or up or not pulled), but clocks can be masked, gated > > > > or simply disabled - this does not imply their signal level. > > > > > > > > > > Signed-off-by: Vikas Sajjan <vikas.sajjan@linaro.org> > > > > > > --- > > > > > > > > > > > > Changes since v3: > > > > > > - added clk_prepare() in fimd_probe() and clk_unprepare() > > > > > > in > > > > > > fimd_remove()> > > > > > > > > > > > > as suggested by Viresh Kumar <viresh.kumar@linaro.org> > > > > > > > > > > > > Changes since v2: > > > > > > - moved clk_prepare_enable() and clk_disable_unprepare() > > > > > > from > > > > > > fimd_probe() to fimd_clock() as suggested by Inki Dae > > > > > > <inki.dae@samsung.com>> > > > > > > > > > > > > Changes since v1: > > > > > > - added error checking for clk_prepare_enable() and also > > > > > > replaced > > > > > > clk_disable() with clk_disable_unprepare() during exit. > > > > > > > > > > > > --- > > > > > > > > > > > > drivers/gpu/drm/exynos/exynos_drm_fimd.c | 14 ++++++++++++-- > > > > > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > > > > > > > > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > > > > > b/drivers/gpu/drm/exynos/exynos_drm_fimd.c index 9537761..aa22370 > > > > > > 100644 > > > > > > --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > > > > > +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c > > > > > > @@ -934,6 +934,16 @@ static int fimd_probe(struct platform_device > > > > > > *pdev)> > > > > > > > > > > > > return ret; > > > > > > > > > > > > } > > > > > > > > > > > > + ret = clk_prepare(ctx->bus_clk); > > > > > > + if (ret < 0) > > > > > > + return ret; > > > > > > + > > > > > > + ret = clk_prepare(ctx->lcd_clk); > > > > > > + if (ret < 0) { > > > > > > + clk_unprepare(ctx->bus_clk); > > > > > > + return ret; > > > > > > + } > > > > > > + > > > > > > > > Why not just simply use clk_prepare_enable() instead of all calls to > > > > clk_enable() in the driver? > > > > > > > > Same goes for s/clk_disable/clk_disable_unprepare/ . > > > > > > I agree with you. Using clk_prepare_enable() is more clear. Actually I > > > had already commented on this. Please see the patch v2. But this way > > > also looks good to me. > > > > > > Well, both versions are technically correct and will have the same effect > > for Exynos SoC clocks, since only enable/disable ops change hardware > > state. > > > > However if we look at general meaning of those generic ops, the clock will > > remain prepared for all the time the driver is loaded, even if the device > > > > > > > > Right, so I said previous one is more clear. I gonna revert current one and then merge previous one(v3) > > > > > > > > is runtime suspended. Again on Exynos SoCs this won't have any effect, but > > I think we should respect general Common Clock Framework semantics anyway. > > > > > > > > > > ctx->vidcon0 = pdata->vidcon0; > > > > > > ctx->vidcon1 = pdata->vidcon1; > > > > > > ctx->default_win = pdata->default_win; > > > > > > > > > > > > @@ -981,8 +991,8 @@ static int fimd_remove(struct platform_device > > > > > > *pdev)> > > > > > > > > > > > > if (ctx->suspended) > > > > > > > > > > > > goto out; > > > > > > > > > > > > - clk_disable(ctx->lcd_clk); > > > > > > - clk_disable(ctx->bus_clk); > > > > > > + clk_unprepare(ctx->lcd_clk); > > > > > > + clk_unprepare(ctx->bus_clk); > > > > > > > > > > This looks wrong again.. You still need to call clk_disable() to > > > > > make > > > > > clk enabled > > > > > count zero... > > > > > > > > Viresh is right again here. > > > > > > Ok, you two guys say together this looks wrong so I'd like to take more > > > checking. I thought that clk->clk_enable is 1 at here and it would be 0 > > > by pm_runtimg_put_sync(). Is there any my missing point? > > > > > > You're reasoning is correct, but only assuming that runtime PM is enabled. > > When it is disabled, pm_runtime_put_sync() is a no-op. > > > > Well, after digging into the exynos_drm_fimd driver a bit more, it seems > > like its power management code needs a serious rework, because I was able > > to find more problems: > > > > 1) fimd_activate() does not get called at all if CONFIG_PM_RUNTIME is not > > enabled (except in system-wide suspend callbacks, but this is irrelevant > > to this point) - this means that the hardware is not properly initialized > > without CONFIG_PM_RUNTIME - at least clocks does not get enabled. > > > > 2) pm_runtime_set_suspended() can be used only when runtime PM is disabled > > for the device (i.e. by calling pm_runtime_disable() or not calling > > pm_runtime_enable() at all) - when runtime PM is enabled it is basically a > > no-op returning -EAGAIN error. > > > > So here's my proposed solution: > > > > 1) call fimd_activate() and pm_runtime_set_active() explicitly in > > fimd_probe(), before calling pm_runtime_enable(): > > > > mutex_init(&ctx->lock); > > > > platform_set_drvdata(pdev, ctx); > > + > > + fimd_activate(ctx, true); > > > > + pm_runtime_set_active(dev); > > pm_runtime_enable(dev); > > pm_runtime_get_sync(dev); > > > > This would power up the device even if CONFIG_PM_RUNTIME is not enabled. > > Note that pm_runtime_get_sync() after marking the device as active with > > pm_runtime_set_active() won't result in calling fimd_runtime_resume(), > > because the device is considered already resumed. > > > > 2) in fimd_remove(): > > > > + pm_runtime_disable(dev); > > + > > if (ctx->suspended) > > - goto out; > > + return 0; > > > > > > - clk_disable(ctx->lcd_clk); > > - clk_disable(ctx->bus_clk); > > > > + fimd_activate(ctx, false); > > > > + pm_runtime_put_noidle(dev); > > pm_runtime_set_suspended(dev); > > - pm_runtime_put_sync(dev); > > - > > -out: > > - pm_runtime_disable(dev); > > > > First, pm_runtime_disable() will prevent any further runtime PM operations > > that could change ctx->suspended state. Then, if ctx->suspended is true, > > there is no need to suspend anything and we can leave. Otherwise, we power > > down the hardware manually - which will work with both CONFIG_PM_RUNTIME > > enabled and disabled, and then mark the hardware as suspended and free > > remaining reference in runtime PM core. Note that pm_runtime_put_noidle > > just decreases the reference counter and nothing else. > > > > 3) after those two changes, all that remains is to fix compliance with > > Common Clock Framework, in other words: > > > > s/clk_enable/clk_prepare_enable/ > > > > and > > > > s/clk_disable/clk_disable_unprepare/ > > > Also looks good to me. But what if power domain was disabled without pm > runtime? In this case, you must enable the power domain at machine code or > bootloader somewhere. This way would not only need some hard codes to turn > the power domain on but also not manage power management fully. This is same > as only the use of pm runtime interface(needing some hard codes without pm > runtime) so I don't prefer to add clk_enable/disable to fimd probe(). I quite > tend to force only the use of pm runtime as possible. So please add the hard > codes to machine code or bootloader like you did for power domain if you > want to use drm fimd without pm runtime. That's not how the runtime PM, clock subsystems work: 1) When CONFIG_PM_RUNTIME is disabled, all the used hardware must be kept powered on all the time. 2) Common Clock Framework will always gate all clocks that have zero enable_count. Note that CCF support for Exynos is already merged for 3.10 and it will be the only available clock support method for Exynos. AFAIK, drivers must work correctly in both cases, with CONFIG_PM_RUNTIME enabled and disabled. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday 22 of April 2013 10:44:00 Viresh Kumar wrote: > On 21 April 2013 20:13, Tomasz Figa <tomasz.figa@gmail.com> wrote: > > 3) after those two changes, all that remains is to fix compliance with > > Common Clock Framework, in other words: > > > > s/clk_enable/clk_prepare_enable/ > > > > and > > > > s/clk_disable/clk_disable_unprepare/ > > We don't have to call clk_{un}prepare() everytime for your platform as > you aren't doing anything in it. So just call them once at probe/remove and > call clk_enable/disable everywhere else. Can you assure that in future SoCs, on which this driver will be used, this assumption will still hold true or even that in current Exynos driver this behavior won't be changed? Best regards,
On 04/22/2013 11:56 AM, Tomasz Figa wrote: > On Monday 22 of April 2013 10:44:00 Viresh Kumar wrote: >> On 21 April 2013 20:13, Tomasz Figa <tomasz.figa@gmail.com> wrote: >>> 3) after those two changes, all that remains is to fix compliance with >>> Common Clock Framework, in other words: >>> >>> s/clk_enable/clk_prepare_enable/ >>> >>> and >>> >>> s/clk_disable/clk_disable_unprepare/ >> >> We don't have to call clk_{un}prepare() everytime for your platform as >> you aren't doing anything in it. So just call them once at probe/remove and >> call clk_enable/disable everywhere else. Yes, I agree with that. Additionally clk_(un)prepare must not be called in atomic context, so some drivers will have to work like this anyway. Or the clocks could be prepared/unprepared in the device open/close file op for instance. > Can you assure that in future SoCs, on which this driver will be used, this > assumption will still hold true or even that in current Exynos driver this > behavior won't be changed? -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 04/22/2013 12:03 PM, Inki Dae wrote: > > Also looks good to me. But what if power domain was disabled without pm > > runtime? In this case, you must enable the power domain at machine code or > > bootloader somewhere. This way would not only need some hard codes to turn > > the power domain on but also not manage power management fully. This is same > > as only the use of pm runtime interface(needing some hard codes without pm > > runtime) so I don't prefer to add clk_enable/disable to fimd probe(). I quite > > tend to force only the use of pm runtime as possible. So please add the hard > > codes to machine code or bootloader like you did for power domain if you > > want to use drm fimd without pm runtime. > > That's not how the runtime PM, clock subsystems work: > > 1) When CONFIG_PM_RUNTIME is disabled, all the used hardware must be kept > powered on all the time. > > 2) Common Clock Framework will always gate all clocks that have zero > enable_count. Note that CCF support for Exynos is already merged for 3.10 and > it will be the only available clock support method for Exynos. > > AFAIK, drivers must work correctly in both cases, with CONFIG_PM_RUNTIME > enabled and disabled. > > > Then is the driver worked correctly if the power domain to this device was > disabled at bootloader without CONFIG_PM_RUNTIME and with clk_enable()? I > think, in this case, the device wouldn't be worked correctly because the power > of the device remains off. So you must enable the power domain somewhere. What > is the difference between these two cases? How about making the driver dependant on PM_RUNTIME and making it always use pm_runtime_* API, regardless if the platform actually implements runtime PM or not ? Is there any issue in using the Runtime PM core always, rather than coding any workarounds in drivers when PM_RUNTIME is disabled ? Thanks, Sylwester -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 22 April 2013 15:26, Tomasz Figa <t.figa@samsung.com> wrote: > Can you assure that in future SoCs, on which this driver will be used, this > assumption will still hold true or even that in current Exynos driver this > behavior won't be changed? Probably yes.. Registers for enabling/disabling these clocks should always be on AMBA bus and not on SPI/I2C, i.e. on-soc... and so this will hold true. -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday 22 of April 2013 12:17:39 Sylwester Nawrocki wrote: > On 04/22/2013 12:03 PM, Inki Dae wrote: > > > Also looks good to me. But what if power domain was disabled without > > > pm > > > runtime? In this case, you must enable the power domain at machine > > > code or > > > bootloader somewhere. This way would not only need some hard codes > > > to turn > > > the power domain on but also not manage power management fully. This > > > is same as only the use of pm runtime interface(needing some hard > > > codes without pm runtime) so I don't prefer to add > > > clk_enable/disable to fimd probe(). I quite tend to force only the > > > use of pm runtime as possible. So please add the hard codes to > > > machine code or bootloader like you did for power domain if you > > > want to use drm fimd without pm runtime. > > > > That's not how the runtime PM, clock subsystems work: > > > > 1) When CONFIG_PM_RUNTIME is disabled, all the used hardware must be > > kept > > powered on all the time. > > > > 2) Common Clock Framework will always gate all clocks that have zero > > enable_count. Note that CCF support for Exynos is already merged for > > 3.10 and it will be the only available clock support method for > > Exynos. > > > > AFAIK, drivers must work correctly in both cases, with > > CONFIG_PM_RUNTIME > > enabled and disabled. > > > > Then is the driver worked correctly if the power domain to this device was > > disabled at bootloader without CONFIG_PM_RUNTIME and with clk_enable()? I > > think, in this case, the device wouldn't be worked correctly because the > > power of the device remains off. So you must enable the power domain > > somewhere. What is the difference between these two cases? > > How about making the driver dependant on PM_RUNTIME and making it always > use pm_runtime_* API, regardless if the platform actually implements runtime > PM or not ? Is there any issue in using the Runtime PM core always, rather > than coding any workarounds in drivers when PM_RUNTIME is disabled ? I don't think this is a good idea. This would mean that any user that from some reasons don't want to use PM_RUNTIME, would not be able to use the driver anymore. Rafael, Kevin, do you have any opinion on this? Best regards,
On Monday, April 22, 2013 12:37:36 PM Tomasz Figa wrote: > On Monday 22 of April 2013 12:17:39 Sylwester Nawrocki wrote: > > On 04/22/2013 12:03 PM, Inki Dae wrote: > > > > Also looks good to me. But what if power domain was disabled without > > > > pm > > > > runtime? In this case, you must enable the power domain at machine > > > > code or > > > > bootloader somewhere. This way would not only need some hard codes > > > > to turn > > > > the power domain on but also not manage power management fully. This > > > > is same as only the use of pm runtime interface(needing some hard > > > > codes without pm runtime) so I don't prefer to add > > > > clk_enable/disable to fimd probe(). I quite tend to force only the > > > > use of pm runtime as possible. So please add the hard codes to > > > > machine code or bootloader like you did for power domain if you > > > > want to use drm fimd without pm runtime. > > > > > > That's not how the runtime PM, clock subsystems work: > > > > > > 1) When CONFIG_PM_RUNTIME is disabled, all the used hardware must be > > > kept > > > powered on all the time. > > > > > > 2) Common Clock Framework will always gate all clocks that have zero > > > enable_count. Note that CCF support for Exynos is already merged for > > > 3.10 and it will be the only available clock support method for > > > Exynos. > > > > > > AFAIK, drivers must work correctly in both cases, with > > > CONFIG_PM_RUNTIME > > > enabled and disabled. > > > > > > Then is the driver worked correctly if the power domain to this device was > > > disabled at bootloader without CONFIG_PM_RUNTIME and with clk_enable()? I > > > think, in this case, the device wouldn't be worked correctly because the > > > power of the device remains off. So you must enable the power domain > > > somewhere. What is the difference between these two cases? > > > > How about making the driver dependant on PM_RUNTIME and making it always > > use pm_runtime_* API, regardless if the platform actually implements runtime > > PM or not ? Is there any issue in using the Runtime PM core always, rather > > than coding any workarounds in drivers when PM_RUNTIME is disabled ? > > I don't think this is a good idea. This would mean that any user that from > some reasons don't want to use PM_RUNTIME, would not be able to use the driver > anymore. > > Rafael, Kevin, do you have any opinion on this? I agree. Drivers should work for CONFIG_PM_RUNTIME unset too and static inline stubs for all runtime PM helpers are available in that case. Thanks, Rafael
On Monday 22 of April 2013 12:05:49 Sylwester Nawrocki wrote: > On 04/22/2013 11:56 AM, Tomasz Figa wrote: > > On Monday 22 of April 2013 10:44:00 Viresh Kumar wrote: > >> On 21 April 2013 20:13, Tomasz Figa <tomasz.figa@gmail.com> wrote: > >>> 3) after those two changes, all that remains is to fix compliance with > >>> Common Clock Framework, in other words: > >>> > >>> s/clk_enable/clk_prepare_enable/ > >>> > >>> and > >>> > >>> s/clk_disable/clk_disable_unprepare/ > >> > >> We don't have to call clk_{un}prepare() everytime for your platform as > >> you aren't doing anything in it. So just call them once at probe/remove > >> and > >> call clk_enable/disable everywhere else. > > Yes, I agree with that. Additionally clk_(un)prepare must not be called in > atomic context, so some drivers will have to work like this anyway. > Or the clocks could be prepared/unprepared in the device open/close file op > for instance. Well, I don't think drivers should make any assumptions how particular clk ops are implemented on particular platform. Instead, generic semantics of Common Clock Framework should be obeyed, which AFAIK are: 1) Each clock must be prepared before enabling. 2) clk_prepare() can not be called from atomic contexts. 3) clk_prepare_enable() can be used instead of clk_prepare() + clk_enable() when the driver does not need to enable the clock from atomic context. Since the Exynos DRM FIMD driver does not need to do call any clock operations in atomic contexts, the approach keeping the clock handling as simple as possible would be to just replace all clk_{enable,disable} with clk_{prepare_enable,disable_unprepare}, as I suggested. CCing Mike, the maintainer of Common Clock Framework, since he's the right person to pass any judgements when it is about clocks. Best regards,
2013/4/22 Inki Dae > 2013/4/22 Rafael J. Wysocki <rjw@sisk.pl> > > On Monday, April 22, 2013 12:37:36 PM Tomasz Figa wrote: > > > On Monday 22 of April 2013 12:17:39 Sylwester Nawrocki wrote: > > > > On 04/22/2013 12:03 PM, Inki Dae wrote: > > > > > > Also looks good to me. But what if power domain was disabled without > > > > > > pm > > > > > > runtime? In this case, you must enable the power domain at machine > > > > > > code or > > > > > > bootloader somewhere. This way would not only need some hard codes > > > > > > to turn > > > > > > the power domain on but also not manage power management fully. This > > > > > > is same as only the use of pm runtime interface(needing some hard > > > > > > codes without pm runtime) so I don't prefer to add > > > > > > clk_enable/disable to fimd probe(). I quite tend to force only the > > > > > > use of pm runtime as possible. So please add the hard codes to > > > > > > machine code or bootloader like you did for power domain if you > > > > > > want to use drm fimd without pm runtime. > > > > > > > > > > That's not how the runtime PM, clock subsystems work: > > > > > > > > > > 1) When CONFIG_PM_RUNTIME is disabled, all the used hardware must be > > > > > kept > > > > > powered on all the time. > > > > > > > > > > 2) Common Clock Framework will always gate all clocks that have zero > > > > > enable_count. Note that CCF support for Exynos is already merged for > > > > > 3.10 and it will be the only available clock support method for > > > > > Exynos. > > > > > > > > > > AFAIK, drivers must work correctly in both cases, with > > > > > CONFIG_PM_RUNTIME > > > > > enabled and disabled. > > > > > > > > > > Then is the driver worked correctly if the power domain to this device was > > > > > disabled at bootloader without CONFIG_PM_RUNTIME and with clk_enable()? I > > > > > think, in this case, the device wouldn't be worked correctly because the > > > > > power of the device remains off. So you must enable the power domain > > > > > somewhere. What is the difference between these two cases? > > > > > > > > How about making the driver dependant on PM_RUNTIME and making it always > > > > use pm_runtime_* API, regardless if the platform actually implements runtime > > > > PM or not ? Is there any issue in using the Runtime PM core always, rather > > > > than coding any workarounds in drivers when PM_RUNTIME is disabled ? > > > > > > I don't think this is a good idea. This would mean that any user that from > > > some reasons don't want to use PM_RUNTIME, would not be able to use the driver > > > anymore. > > > > > > Rafael, Kevin, do you have any opinion on this? > > I agree. > > > > Drivers should work for CONFIG_PM_RUNTIME unset too and static inline stubs for > > all runtime PM helpers are available in that case. > > > Hi Rafael, > The embedded system, at least Exynos SoC case, has the power domain device and this device could be enabled only by pm runtime interface. So the device couldn't be worked correctly without turning the power domain on only calling clk_enable(). In this case, the power domain must be enabled at machine code or bootloader. And the machine without CONFIG_PM_RUNTIME would assume that their own drivers always are enabled so the devices would be worked correctly. Is there any my missing point? - Power domain: not controlled if !CONFIG_PM_RUNTIME. Thus, we may assume that every power domain is kept ON from boot time if !CONFIG_PM_RUNTIME. If power domain is kept OFF from boot time (machine init code or bootloader) with !CONFIG_PM_RUNTIME, then it's simple a mistake at BSP writer. - Yes, the clock is still controlled while !CONFIG_PM_RUNTIME. My opinion is also to let probe do clk-enables though I don't want it to have #ifdef or "clk_enable()" in the probe function. Thus, implementing "power_on()"-like function in the driver and let probe() and runtime_pm_get callback call it seems appropriate to me. (that "fimd_active(ctx, true)" is "power-on" to itself, right?) Cheers, MyungJoo -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fimd.c b/drivers/gpu/drm/exynos/exynos_drm_fimd.c index 9537761..aa22370 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_fimd.c +++ b/drivers/gpu/drm/exynos/exynos_drm_fimd.c @@ -934,6 +934,16 @@ static int fimd_probe(struct platform_device *pdev) return ret; } + ret = clk_prepare(ctx->bus_clk); + if (ret < 0) + return ret; + + ret = clk_prepare(ctx->lcd_clk); + if (ret < 0) { + clk_unprepare(ctx->bus_clk); + return ret; + } + ctx->vidcon0 = pdata->vidcon0; ctx->vidcon1 = pdata->vidcon1; ctx->default_win = pdata->default_win; @@ -981,8 +991,8 @@ static int fimd_remove(struct platform_device *pdev) if (ctx->suspended) goto out; - clk_disable(ctx->lcd_clk); - clk_disable(ctx->bus_clk); + clk_unprepare(ctx->lcd_clk); + clk_unprepare(ctx->bus_clk); pm_runtime_set_suspended(dev); pm_runtime_put_sync(dev);
While migrating to common clock framework (CCF), I found that the FIMD clocks were pulled down by the CCF. If CCF finds any clock(s) which has NOT been claimed by any of the drivers, then such clock(s) are PULLed low by CCF. Calling clk_prepare() for FIMD clocks fixes the issue. This patch also replaces clk_disable() with clk_unprepare() during exit, since clk_prepare() is called in fimd_probe(). Signed-off-by: Vikas Sajjan <vikas.sajjan@linaro.org> --- Changes since v3: - added clk_prepare() in fimd_probe() and clk_unprepare() in fimd_remove() as suggested by Viresh Kumar <viresh.kumar@linaro.org> Changes since v2: - moved clk_prepare_enable() and clk_disable_unprepare() from fimd_probe() to fimd_clock() as suggested by Inki Dae <inki.dae@samsung.com> Changes since v1: - added error checking for clk_prepare_enable() and also replaced clk_disable() with clk_disable_unprepare() during exit. --- drivers/gpu/drm/exynos/exynos_drm_fimd.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)