On 3 July 2012 17:27, Girish K S <girish.shivananjappa@xxxxxxxxxx> wrote:
> On 3 July 2012 17:01, Aaron Lu <aaron.lu@xxxxxxx> wrote:
>> 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.
> Thanks for the explanation. is it possible to make a separate local
> function for this. Since mmc_host_ops has a member .execute_tuning
> which takes 2 parameters that are called from respective sd/mmc/sdio
> card files. there might be conflict
Sorry i just read it wrongly (function has only 1 param).
>>
>> -Aaron
>>
>>> > spin_lock_irqsave(&host->lock, flags);
>>> >
>>> > /* Restore original mmc_request structure */
>>> > --
>>> > 1.7.11.1.3.g4c8a9db
>>> >
>>> >
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