Hi Arindam, Thank you for the review. Please find few comments inline. > -----Original Message----- > From: Nath, Arindam [mailto:Arindam.Nath@xxxxxxx] > Sent: Tuesday, August 02, 2011 12:38 PM > To: Chris Ball; Subhash Jadavani > Cc: linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; Philip > Rakity; zhangfei gao > Subject: RE: [PATCH] mmc: sd: UHS-I bus speed should be set last in UHS > initialization > > Hi Subhash, > > > > -----Original Message----- > > From: Chris Ball [mailto:cjb@xxxxxxxxxx] > > Sent: Tuesday, August 02, 2011 1:40 AM > > To: Subhash Jadavani > > Cc: linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; Nath, > > Arindam > > Subject: Re: [PATCH] mmc: sd: UHS-I bus speed should be set last in > UHS > > initialization > > > > Hi Subhash, adding Arindam for review, > > > > On Mon, Aug 01 2011, Subhash Jadavani wrote: > > > mmc_sd_init_uhs_card function sets the driver type, current limit > > > and bus speed mode on card as well as on host controller side. > > > > > > Currently bus speed mode is set by sending CMD6 to card and > > > immediately setting the timing mode in host controller. But > > > then before initiating tuning sequence, it also tries to set > > > current limit by sending CMD6 to card which results in data > > > timeout errors in controller if bus speed mode is SDR50/SDR104 > mode. > > > > > > So basically bus speed mode should be set only after current limit > > > is set in the card and immediately after setting the bus speed > mode, > > > tuning sequence should be initiated. > > > > > > Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx> > > > --- > > > drivers/mmc/core/sd.c | 57 ++++++++++++++++++++++++++++++++----- > -- > > --------- > > > 1 files changed, 38 insertions(+), 19 deletions(-) > > > > > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > > > index ff27741..d257496 100644 > > > --- a/drivers/mmc/core/sd.c > > > +++ b/drivers/mmc/core/sd.c > > > @@ -459,10 +459,9 @@ static int sd_select_driver_type(struct > mmc_card > > *card, u8 *status) > > > return 0; > > > } > > > > > > -static int sd_set_bus_speed_mode(struct mmc_card *card, u8 > *status) > > > +static int sd_get_bus_speed_mode(struct mmc_card *card) > > > { > > > - unsigned int bus_speed = 0, timing = 0; > > > - int err; > > > + int bus_speed = 0; > > > > > > /* > > > * If the host doesn't support any of the UHS-I modes, fallback > > on > > > @@ -470,37 +469,56 @@ static int sd_set_bus_speed_mode(struct > > mmc_card *card, u8 *status) > > > */ > > > if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | > > > MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) > > > - return 0; > > > + return -EINVAL; > > We should not return -EINVAL here, because this is not an error > condition. This would simply mean that the card and host controller > will fall back to using the default bus speed, and should still be > operable. Check the comment below too. Return value of this function gets used in sd_set_bus_speed_mode() function and compared against all the valid bus speed modes. If we choose to return 0 from here then '0' corresponds to valid bus speed mode 'UHS_SDR12_BUS_SPEED'. #define UHS_SDR12_BUS_SPEED 0 #define UHS_SDR25_BUS_SPEED 1 #define UHS_SDR50_BUS_SPEED 2 #define UHS_SDR104_BUS_SPEED 3 #define UHS_DDR50_BUS_SPEED 4 If we don't want to return the error value from this function then we can basically remove following check from this *get* function and move it to each *set* function before calling *get*. Please see more comments inline in *set* functions below. if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) return -EINVAL; > > > > > > > if ((card->host->caps & MMC_CAP_UHS_SDR104) && > > > (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR104)) { > > > bus_speed = UHS_SDR104_BUS_SPEED; > > > - timing = MMC_TIMING_UHS_SDR104; > > > - card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR; > > > } else if ((card->host->caps & MMC_CAP_UHS_DDR50) && > > > (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_DDR50)) { > > > bus_speed = UHS_DDR50_BUS_SPEED; > > > - timing = MMC_TIMING_UHS_DDR50; > > > - card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR; > > > } else if ((card->host->caps & (MMC_CAP_UHS_SDR104 | > > > MMC_CAP_UHS_SDR50)) && (card->sw_caps.sd3_bus_mode & > > > SD_MODE_UHS_SDR50)) { > > > bus_speed = UHS_SDR50_BUS_SPEED; > > > - timing = MMC_TIMING_UHS_SDR50; > > > - card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR; > > > } else if ((card->host->caps & (MMC_CAP_UHS_SDR104 | > > > MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25)) && > > > (card->sw_caps.sd3_bus_mode & SD_MODE_UHS_SDR25)) { > > > bus_speed = UHS_SDR25_BUS_SPEED; > > > - timing = MMC_TIMING_UHS_SDR25; > > > - card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR; > > > } else if ((card->host->caps & (MMC_CAP_UHS_SDR104 | > > > MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR25 | > > > MMC_CAP_UHS_SDR12)) && (card->sw_caps.sd3_bus_mode & > > > SD_MODE_UHS_SDR12)) { > > > bus_speed = UHS_SDR12_BUS_SPEED; > > > + } > > > + > > > + return bus_speed; > > > +} > > > + > > > +static int sd_set_bus_speed_mode(struct mmc_card *card, u8 > *status) > > > +{ > > > + int err, bus_speed; > > > + unsigned int timing = 0; > > > + We need add this check here. if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) return 0; > > > + bus_speed = sd_get_bus_speed_mode(card); > > > + > > > + if (bus_speed == UHS_SDR104_BUS_SPEED) { > > > + timing = MMC_TIMING_UHS_SDR104; > > > + card->sw_caps.uhs_max_dtr = UHS_SDR104_MAX_DTR; > > > + } else if (bus_speed == UHS_DDR50_BUS_SPEED) { > > > + timing = MMC_TIMING_UHS_DDR50; > > > + card->sw_caps.uhs_max_dtr = UHS_DDR50_MAX_DTR; > > > + } else if (bus_speed == UHS_SDR50_BUS_SPEED) { > > > + timing = MMC_TIMING_UHS_SDR50; > > > + card->sw_caps.uhs_max_dtr = UHS_SDR50_MAX_DTR; > > > + } else if (bus_speed == UHS_SDR25_BUS_SPEED) { > > > + timing = MMC_TIMING_UHS_SDR25; > > > + card->sw_caps.uhs_max_dtr = UHS_SDR25_MAX_DTR; > > > + } else if (bus_speed == UHS_SDR12_BUS_SPEED) { > > > timing = MMC_TIMING_UHS_SDR12; > > > card->sw_caps.uhs_max_dtr = UHS_SDR12_MAX_DTR; > > > + } else { > > > + return -EINVAL; > > > } > > > > Minor change: I think "switch (sd_get_bus_speed_mode(card))" would be > > cleaner. Yes, we can replace it with switch. I will do it next patch rev. > > > > > > > > card->sd_bus_speed = bus_speed; > > > @@ -522,6 +540,7 @@ static int sd_set_bus_speed_mode(struct > mmc_card > > *card, u8 *status) > > > static int sd_set_current_limit(struct mmc_card *card, u8 *status) > > > { > > > int current_limit = 0; > > > + unsigned int bus_speed = sd_get_bus_speed_mode(card); > > > int err; We need add this check here. if (!(card->host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 | MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))) return 0; > > > > > > /* > > > @@ -529,9 +548,9 @@ static int sd_set_current_limit(struct mmc_card > > *card, u8 *status) > > > * bus speed modes. For other bus speed modes, we set the default > > > * current limit of 200mA. > > > */ > > > - if ((card->sd_bus_speed == UHS_SDR50_BUS_SPEED) || > > > - (card->sd_bus_speed == UHS_SDR104_BUS_SPEED) || > > > - (card->sd_bus_speed == UHS_DDR50_BUS_SPEED)) { > > > + if ((bus_speed == UHS_SDR50_BUS_SPEED) || > > > + (bus_speed == UHS_SDR104_BUS_SPEED) || > > > + (bus_speed == UHS_DDR50_BUS_SPEED)) { > > > if (card->host->caps & MMC_CAP_MAX_CURRENT_800) { > > > if (card->sw_caps.sd3_curr_limit & > > SD_MAX_CURRENT_800) > > > current_limit = SD_SET_CURRENT_LIMIT_800; > > > @@ -613,13 +632,13 @@ static int mmc_sd_init_uhs_card(struct > mmc_card > > *card) > > > if (err) > > > goto out; > > > > > > - /* Set bus speed mode of the card */ > > > - err = sd_set_bus_speed_mode(card, status); > > > + /* Set current limit for the card */ > > > + err = sd_set_current_limit(card, status); > > > if (err) > > > goto out; > > > > > > - /* Set current limit for the card */ > > > - err = sd_set_current_limit(card, status); > > > + /* Set bus speed mode of the card */ > > > + err = sd_set_bus_speed_mode(card, status); > > Now supposing that we return -EINVAL here, then that would imply that > mmc_sd_init_uhs_card() failed, but that should not be the case. Like I > mentioned before, the card should still be operable using default speed > mode. When you say Default speed mode, does it mean SDR12 mode? Thanks, Subhash > > Thanks, > Arindam > > > > if (err) > > > goto out; > > > > > > > Thanks, > > > > - Chris. > > -- > > Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/> > > One Laptop Per Child > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
