| Message ID | 1474422233-29355-4-git-send-email-shawn.lin@rock-chips.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 21 September 2016 at 03:43, Shawn Lin <shawn.lin@rock-chips.com> wrote: > Per JESD84-B51 P69, Host need to change frequency to <=52MHz after > setting HS_TIMING to 0x1, and host may changes frequency to <= 200MHz > after setting HS_TIMING to 0x3. It seems there is no difference if > we don't change frequency to <= 52MHz as f_init is already less than > 52MHz. But actually it does make difference. When doing compatibility > test we see failures for some eMMC devices without changing the > frequency to hs_max_dtr. And let's read the spec again, we could see > that "Host may changes frequency to 200MHz" implies that it's not > mandatory. But the "Host need to change frequency to <= 52MHz" implies > that we should do this. I don't get this. Are you saying that f_init > 52 MHz? That should not be impossible, right!? So either the core has changed the clock rate by mistake at some other execution path, or the host driver didn't set the correct clock rate the first time when invoked via mmc_power_up()? Kind regards Uffe > > Reported-by: Xiao Yao <xiaoyao@rock-chips.com> > Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> > --- > > drivers/mmc/core/mmc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c > index 3163bb9..989d37e 100644 > --- a/drivers/mmc/core/mmc.c > +++ b/drivers/mmc/core/mmc.c > @@ -1282,6 +1282,8 @@ static int mmc_select_hs400es(struct mmc_card *card) > if (err) > goto out_err; > > + mmc_set_clock(host, card->ext_csd.hs_max_dtr); > + > err = mmc_switch_status(card); > if (err) > goto out_err; > -- > 2.3.7 > >
Hi ulf, 在 2016/9/22 17:38, Ulf Hansson 写道: > On 21 September 2016 at 03:43, Shawn Lin <shawn.lin@rock-chips.com> wrote: >> Per JESD84-B51 P69, Host need to change frequency to <=52MHz after >> setting HS_TIMING to 0x1, and host may changes frequency to <= 200MHz >> after setting HS_TIMING to 0x3. It seems there is no difference if >> we don't change frequency to <= 52MHz as f_init is already less than >> 52MHz. But actually it does make difference. When doing compatibility >> test we see failures for some eMMC devices without changing the >> frequency to hs_max_dtr. And let's read the spec again, we could see >> that "Host may changes frequency to 200MHz" implies that it's not >> mandatory. But the "Host need to change frequency to <= 52MHz" implies >> that we should do this. > > I don't get this. Are you saying that f_init > 52 MHz? That should not > be impossible, right!? nope, I was saying that the spec implies we to set clock after setting HS_TIMING to 0x1 when doing hs400es selection. I thought there is no difference because the spec says "Host need to change frequency to <= 52MHz", and the f_init(<=400k) is <= 52MHz, right? So I didn't set clock to hs_max_dtr. But I think I misunderstood the spec, so this patch will fix this. > > So either the core has changed the clock rate by mistake at some other > execution path, or the host driver didn't set the correct clock rate > the first time when invoked via mmc_power_up()? > > Kind regards > Uffe > >> >> Reported-by: Xiao Yao <xiaoyao@rock-chips.com> >> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> >> --- >> >> drivers/mmc/core/mmc.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c >> index 3163bb9..989d37e 100644 >> --- a/drivers/mmc/core/mmc.c >> +++ b/drivers/mmc/core/mmc.c >> @@ -1282,6 +1282,8 @@ static int mmc_select_hs400es(struct mmc_card *card) >> if (err) >> goto out_err; >> >> + mmc_set_clock(host, card->ext_csd.hs_max_dtr); >> + >> err = mmc_switch_status(card); >> if (err) >> goto out_err; >> -- >> 2.3.7 >> >> > > >
On 22 September 2016 at 12:06, Shawn Lin <shawn.lin@rock-chips.com> wrote: > Hi ulf, > > 在 2016/9/22 17:38, Ulf Hansson 写道: >> >> On 21 September 2016 at 03:43, Shawn Lin <shawn.lin@rock-chips.com> wrote: >>> >>> Per JESD84-B51 P69, Host need to change frequency to <=52MHz after >>> setting HS_TIMING to 0x1, and host may changes frequency to <= 200MHz >>> after setting HS_TIMING to 0x3. It seems there is no difference if >>> we don't change frequency to <= 52MHz as f_init is already less than >>> 52MHz. But actually it does make difference. When doing compatibility >>> test we see failures for some eMMC devices without changing the >>> frequency to hs_max_dtr. And let's read the spec again, we could see >>> that "Host may changes frequency to 200MHz" implies that it's not >>> mandatory. But the "Host need to change frequency to <= 52MHz" implies >>> that we should do this. >> >> >> I don't get this. Are you saying that f_init > 52 MHz? That should not >> be impossible, right!? > > > nope, I was saying that the spec implies we to set clock after > setting HS_TIMING to 0x1 when doing hs400es selection. > > I thought there is no difference because the spec says "Host need to > change frequency to <= 52MHz", and the f_init(<=400k) is <= 52MHz, > right? So I didn't set clock to hs_max_dtr. But I think I misunderstood > the spec, so this patch will fix this. Okay, I see what you mean now! In other words: The card expects the clock rate to increase from the current used f_init (which is <= 400KHz), but still being <= 52MHz, when you have set HS_TIMING to 0x1. Okay, we can do that change! Could you try to improve the change log a little bit or you want me to help? Kind regards Uffe
On 2016/9/22 18:21, Ulf Hansson wrote: > On 22 September 2016 at 12:06, Shawn Lin <shawn.lin@rock-chips.com> wrote: >> Hi ulf, >> >> 在 2016/9/22 17:38, Ulf Hansson 写道: >>> >>> On 21 September 2016 at 03:43, Shawn Lin <shawn.lin@rock-chips.com> wrote: >>>> >>>> Per JESD84-B51 P69, Host need to change frequency to <=52MHz after >>>> setting HS_TIMING to 0x1, and host may changes frequency to <= 200MHz >>>> after setting HS_TIMING to 0x3. It seems there is no difference if >>>> we don't change frequency to <= 52MHz as f_init is already less than >>>> 52MHz. But actually it does make difference. When doing compatibility >>>> test we see failures for some eMMC devices without changing the >>>> frequency to hs_max_dtr. And let's read the spec again, we could see >>>> that "Host may changes frequency to 200MHz" implies that it's not >>>> mandatory. But the "Host need to change frequency to <= 52MHz" implies >>>> that we should do this. >>> >>> >>> I don't get this. Are you saying that f_init > 52 MHz? That should not >>> be impossible, right!? >> >> >> nope, I was saying that the spec implies we to set clock after >> setting HS_TIMING to 0x1 when doing hs400es selection. >> >> I thought there is no difference because the spec says "Host need to >> change frequency to <= 52MHz", and the f_init(<=400k) is <= 52MHz, >> right? So I didn't set clock to hs_max_dtr. But I think I misunderstood >> the spec, so this patch will fix this. > > Okay, I see what you mean now! > > In other words: > The card expects the clock rate to increase from the current used > f_init (which is <= 400KHz), but still being <= 52MHz, when you have > set HS_TIMING to 0x1. > > Okay, we can do that change! Could you try to improve the change log a > little bit or you want me to help? yep, I could change the commit msg a bit and fix another copy-paste error, then respin v2. BTW, I noticed you have applied one of these 5 patches, so I will remove that one for V2. Thanks, Ulf. > > Kind regards > Uffe > > >
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 3163bb9..989d37e 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1282,6 +1282,8 @@ static int mmc_select_hs400es(struct mmc_card *card) if (err) goto out_err; + mmc_set_clock(host, card->ext_csd.hs_max_dtr); + err = mmc_switch_status(card); if (err) goto out_err;
Per JESD84-B51 P69, Host need to change frequency to <=52MHz after setting HS_TIMING to 0x1, and host may changes frequency to <= 200MHz after setting HS_TIMING to 0x3. It seems there is no difference if we don't change frequency to <= 52MHz as f_init is already less than 52MHz. But actually it does make difference. When doing compatibility test we see failures for some eMMC devices without changing the frequency to hs_max_dtr. And let's read the spec again, we could see that "Host may changes frequency to 200MHz" implies that it's not mandatory. But the "Host need to change frequency to <= 52MHz" implies that we should do this. Reported-by: Xiao Yao <xiaoyao@rock-chips.com> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> --- drivers/mmc/core/mmc.c | 2 ++ 1 file changed, 2 insertions(+)