Hi,
On Tue, Jul 03, 2012 at 03:28:28PM +0530, Girish K S wrote:
> On 3 July 2012 14:57, Aaron Lu <aaron.lu@xxxxxxx> wrote:
> > V2:
> > Fix for SDIO case: both SD and SDIO cards use cmd19 while eMMC use cmd21.
> >
> > V1:
> > For SD hosts using retuning mode 1, when retuning timer expired, it will
> > need to do retuning in sdhci_request before processing the actual
> > request. But the retuning command is fixed: cmd19 for SD card and cmd21
> > for eMMC card, so we can't use the original request's command to do the
> > tuning.
> >
> > And since the tuning command depends on the card type atteched to the
> > host, we will need to know the card type to use the correct tuning
> > command.
> >
> > Cc: stable <stable@xxxxxxxxxxxxxxx> [3.3+]
> > Signed-off-by: Aaron Lu <aaron.lu@xxxxxxx>
> > ---
> > drivers/mmc/host/sdhci.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index f76736b..4e53e6b 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -27,6 +27,7 @@
> >
> > #include <linux/mmc/mmc.h>
> > #include <linux/mmc/host.h>
> > +#include <linux/mmc/card.h>
> >
> > #include "sdhci.h"
> >
> > @@ -1245,6 +1246,7 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > struct sdhci_host *host;
> > bool present;
> > unsigned long flags;
> > + u32 tuning_opcode;
> >
> > host = mmc_priv(mmc);
> >
> > @@ -1292,8 +1294,12 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > */
> > if ((host->flags & SDHCI_NEEDS_RETUNING) &&
> > !(present_state & (SDHCI_DOING_WRITE | SDHCI_DOING_READ))) {
> > + /* eMMC uses cmd21 while sd and sdio use cmd19 */
> > + tuning_opcode = mmc->card->type == MMC_TYPE_MMC ?
> > + MMC_SEND_TUNING_BLOCK_HS200 :
> > + MMC_SEND_TUNING_BLOCK;
> > spin_unlock_irqrestore(&host->lock, flags);
> > - sdhci_execute_tuning(mmc, mrq->cmd->opcode);
> > + sdhci_execute_tuning(mmc, tuning_opcode);
> dont you think the previous implementation does the same. It is
> already handled by introducing the 2nd parameter.
Suppose the following scenario:
mmc_start_request (e.g. mrq->cmd->opcode is 18 for this call)
-> host->ops->request
(sdhci's retuning timer expired, the flag SDHCI_NEEDS_RETUNING is set)
-> sdhci_request
-> sdhci_execute_tuning will be called before processing the
actual request due to retuning's requirement, but with the wrong command
opcode(cmd18) instead of cmd19 for sd/sdio or cmd21 for emmc.
The problem is with retuning, for normal explicit calls of
sdhci_execute_tuning, there is no problem with the code. But when
retuning is required, sdhci_execute_retuning will be executed implicitly
to the above layer and we have to use the right tuning command instead of
the current processing command, which can be any of the valid sd/sdio/mmc
commands.
-Aaron
> > spin_lock_irqsave(&host->lock, flags);
> >
> > /* Restore original mmc_request structure */
> > --
> > 1.7.11.1.3.g4c8a9db
> >
> >
--
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
