Hi Adrian, Thanks a lot for your suggestion. I have sent out the new version patch-set. Please help to review :) Best regards, Yangbo Lu > -----Original Message----- > From: Adrian Hunter [mailto:adrian.hunter@xxxxxxxxx] > Sent: Thursday, March 23, 2017 3:04 PM > To: Y.B. Lu; linux-mmc@xxxxxxxxxxxxxxx; ulf.hansson@xxxxxxxxxx; Rob > Herring; Mark Rutland; Catalin Marinas; Will Deacon > Cc: devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > Xiaobo Xie > Subject: Re: [v2, 4/7] mmc: sdhci: add a quirk to restore delay in tuning > > On 03/03/17 10:18, Yangbo Lu wrote: > > There was a mdelay between tuning cycles which is removed since eMMC > > spec didn't require that. However it's observed that eSDHC needed this > > delay for HS200 successful tuning. Maybe it's also needed for some > > other controllers. This patch is to add a quirk to fix it. > > > > Fixes: 197160d52e85 ("mmc: sdhci: remove mdelay in eMMC tuning") > > Signed-off-by: Yangbo Lu <yangbo.lu@xxxxxxx> > > --- > > I would prefer to do something like this: > > --- > From: Adrian Hunter <adrian.hunter@xxxxxxxxx> > Date: Thu, 23 Mar 2017 08:54:06 +0200 > Subject: [PATCH] mmc: sdhci: Control the delay between tuning commands > > The delay between tuning commands for SD cards is not part of the > specification. A driver that needs it probably needs it for eMMC too, > whereas most drivers would probably like to set it to 0. Make it a host > member (host->tuning_delay) that defaults to the existing behaviour. > Drivers can set it to zero to eliminate the delay, or set it to a > positive value to always have a delay. > > Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> > --- > drivers/mmc/host/sdhci.c | 11 ++++++++--- drivers/mmc/host/sdhci.h | 1 > + > 2 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index > a33102fc800b..2fc33485df1d 100644 > --- a/drivers/mmc/host/sdhci.c > +++ b/drivers/mmc/host/sdhci.c > @@ -2100,9 +2100,9 @@ static void __sdhci_execute_tuning(struct > sdhci_host *host, u32 opcode) > break; > } > > - /* eMMC spec does not require a delay between tuning cycles > */ > - if (opcode == MMC_SEND_TUNING_BLOCK) > - mdelay(1); > + /* Spec does not require a delay between tuning cycles */ > + if (host->tuning_delay > 0) > + mdelay(host->tuning_delay); > } > > pr_info("%s: Tuning failed, falling back to fixed sampling clock\n", > @@ -2164,6 +2164,9 @@ int sdhci_execute_tuning(struct mmc_host *mmc, u32 > opcode) > > host->mmc->retune_period = tuning_count; > > + if (host->tuning_delay < 0) > + host->tuning_delay = opcode == MMC_SEND_TUNING_BLOCK; > + > sdhci_start_tuning(host); > > __sdhci_execute_tuning(host, opcode); > @@ -3108,6 +3111,8 @@ struct sdhci_host *sdhci_alloc_host(struct device > *dev, > host->cqe_ier = SDHCI_CQE_INT_MASK; > host->cqe_err_ier = SDHCI_CQE_INT_ERR_MASK; > > + host->tuning_delay = -1; > + > return host; > } > > diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h index > 35b41da0a636..b0f416fc9548 100644 > --- a/drivers/mmc/host/sdhci.h > +++ b/drivers/mmc/host/sdhci.h > @@ -538,6 +538,7 @@ struct sdhci_host { > #define SDHCI_TUNING_MODE_1 0 > #define SDHCI_TUNING_MODE_2 1 > #define SDHCI_TUNING_MODE_3 2 > + int tuning_delay; /* Delay (ms) between tuning > commands */ > > unsigned long private[0] ____cacheline_aligned; }; > -- > 1.9.1 > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
