| Message ID | 1426672363-30667-10-git-send-email-tomeu.vizoso@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Mar 18, 2015 at 10:52:24AM +0100, Tomeu Vizoso wrote: > As there isn't a way for the firmware on the Nyan chromebooks to hand > over the display to the kernel. Perhaps this should be more explicit. I'm assuming this somehow breaks on Nyan for you because we try to reprogram the SOR from an already initialized state and that doesn't actually work? Your current commit message doesn't make this sound like a fix for an actual problem. > Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> > Acked-by: Stephen Warren <swarren@nvidia.com> > Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> > --- > drivers/gpu/drm/tegra/sor.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c > index 2afe478..e6caacc 100644 > --- a/drivers/gpu/drm/tegra/sor.c > +++ b/drivers/gpu/drm/tegra/sor.c > @@ -1458,6 +1458,20 @@ static int tegra_sor_probe(struct platform_device *pdev) > > mutex_init(&sor->lock); > > + err = reset_control_assert(sor->rst); > + if (err < 0) { > + dev_err(&pdev->dev, "failed to assert SOR reset: %d\n", err); > + return err; > + } > + > + msleep(20); > + > + err = reset_control_deassert(sor->rst); > + if (err < 0) { > + dev_err(&pdev->dev, "failed to deassert SOR reset: %d\n", err); > + return err; > + } If you do this in ->probe() there's a potentially long time where the screen will remain black. A better location for this is probably in the tegra_sor_init() function. That puts it closer to where the output is reinitialized and potentially reduces the time where no display is available. Also it is a more logical place for this code, since the clocks are also enabled in tegra_sor_init(). Technically resets on Tegra are synchronous and therefore the reset should happen across the clk_prepare_enable() call of the primary module clock. So I'd expect something like this: err = reset_control_assert(sor->rst); ... err = clk_prepare_enable(sor->clk); ... /* sleep */ err = reset_control_deassert(sor->rst); ... Where sleep can probably be significantly shorter than 20 ms. I think the documentation says that 2 us are typically enough. That said, I'm fine with leaving in 20 ms, it shouldn't matter much in the overall boot-time. Also, since this will need to be revisited once we have proper hand-over from firmware to kernel, do you mind adding a comment along these lines: /* * XXX: Remove this reset once proper hand-over from firmware to * kernel is possible. */ ? Thanks, Thierry
diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c index 2afe478..e6caacc 100644 --- a/drivers/gpu/drm/tegra/sor.c +++ b/drivers/gpu/drm/tegra/sor.c @@ -1458,6 +1458,20 @@ static int tegra_sor_probe(struct platform_device *pdev) mutex_init(&sor->lock); + err = reset_control_assert(sor->rst); + if (err < 0) { + dev_err(&pdev->dev, "failed to assert SOR reset: %d\n", err); + return err; + } + + msleep(20); + + err = reset_control_deassert(sor->rst); + if (err < 0) { + dev_err(&pdev->dev, "failed to deassert SOR reset: %d\n", err); + return err; + } + err = host1x_client_register(&sor->client); if (err < 0) { dev_err(&pdev->dev, "failed to register host1x client: %d\n",