[PATCH] mmc: core: Improve fallback to speed modes if eMMC HS200 fails

[PATCH] mmc: core: Improve fallback to speed modes if eMMC HS200 fails

[Ulf Hansson]

In the error path of mmc_select_hs200() we are trying our best to restore
the card/host into a valid state. This makes sense, especially if we
encounter a simple switch error (-EBADMSG). However, rather than then
continue with using the legacy speed mode, let's try the other better speed
modes first. Additionally, let's update the card->mmc_avail_type to avoid
us from trying a broken HS200 mode again.

In an Amlogic S905W based TV box where the switch to HS200 mode fails for
the eMMC, this allows us to use the eMMC in DDR mode in favor of the legacy
mode, which greatly improves the performance.

Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/core/mmc.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 141f851c9f58..6e7db45cb8e0 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1518,13 +1518,23 @@ static int mmc_select_timing(struct mmc_card *card)
 	if (!mmc_can_ext_csd(card))
 		goto bus_speed;
 
-	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
 		err = mmc_select_hs400es(card);
-	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
+		goto out;
+	}
+
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200) {
 		err = mmc_select_hs200(card);
-	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
+		if (err == -EBADMSG)
+			card->mmc_avail_type &= ~EXT_CSD_CARD_TYPE_HS200;
+		else
+			goto out;
+	}
+
+	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
 		err = mmc_select_hs(card);
 
+out:
 	if (err && err != -EBADMSG)
 		return err;
 
-- 
2.25.1

Re: [PATCH] mmc: core: Improve fallback to speed modes if eMMC HS200 fails

[Ulf Hansson]

On Thu, 3 Mar 2022 at 17:45, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
> In the error path of mmc_select_hs200() we are trying our best to restore
> the card/host into a valid state. This makes sense, especially if we
> encounter a simple switch error (-EBADMSG). However, rather than then
> continue with using the legacy speed mode, let's try the other better speed
> modes first. Additionally, let's update the card->mmc_avail_type to avoid
> us from trying a broken HS200 mode again.
>
> In an Amlogic S905W based TV box where the switch to HS200 mode fails for
> the eMMC, this allows us to use the eMMC in DDR mode in favor of the legacy
> mode, which greatly improves the performance.
>
> Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Heiner, does this solve your problems? Can you perhaps run some tests
at your side to see how it works for you?

Kind regards
Uffe

> ---
>  drivers/mmc/core/mmc.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 141f851c9f58..6e7db45cb8e0 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1518,13 +1518,23 @@ static int mmc_select_timing(struct mmc_card *card)
>         if (!mmc_can_ext_csd(card))
>                 goto bus_speed;
>
> -       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
>                 err = mmc_select_hs400es(card);
> -       else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
> +               goto out;
> +       }
> +
> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200) {
>                 err = mmc_select_hs200(card);
> -       else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
> +               if (err == -EBADMSG)
> +                       card->mmc_avail_type &= ~EXT_CSD_CARD_TYPE_HS200;
> +               else
> +                       goto out;
> +       }
> +
> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
>                 err = mmc_select_hs(card);
>
> +out:
>         if (err && err != -EBADMSG)
>                 return err;
>
> --
> 2.25.1
>

Re: [PATCH] mmc: core: Improve fallback to speed modes if eMMC HS200 fails

[Heiner Kallweit]

On 14.03.2022 11:54, Ulf Hansson wrote:
> On Thu, 3 Mar 2022 at 17:45, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>
>> In the error path of mmc_select_hs200() we are trying our best to restore
>> the card/host into a valid state. This makes sense, especially if we
>> encounter a simple switch error (-EBADMSG). However, rather than then
>> continue with using the legacy speed mode, let's try the other better speed
>> modes first. Additionally, let's update the card->mmc_avail_type to avoid
>> us from trying a broken HS200 mode again.
>>
>> In an Amlogic S905W based TV box where the switch to HS200 mode fails for
>> the eMMC, this allows us to use the eMMC in DDR mode in favor of the legacy
>> mode, which greatly improves the performance.
>>
>> Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> 
> Heiner, does this solve your problems? Can you perhaps run some tests
> at your side to see how it works for you?
> 

Tested-by: Heiner Kallweit <hkallweit1@gmail.com>

> Kind regards
> Uffe
> 
Heiner

>> ---
>>  drivers/mmc/core/mmc.c | 16 +++++++++++++---
>>  1 file changed, 13 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 141f851c9f58..6e7db45cb8e0 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1518,13 +1518,23 @@ static int mmc_select_timing(struct mmc_card *card)
>>         if (!mmc_can_ext_csd(card))
>>                 goto bus_speed;
>>
>> -       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES)
>> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400ES) {
>>                 err = mmc_select_hs400es(card);
>> -       else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
>> +               goto out;
>> +       }
>> +
>> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200) {
>>                 err = mmc_select_hs200(card);
>> -       else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
>> +               if (err == -EBADMSG)
>> +                       card->mmc_avail_type &= ~EXT_CSD_CARD_TYPE_HS200;
>> +               else
>> +                       goto out;
>> +       }
>> +
>> +       if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
>>                 err = mmc_select_hs(card);
>>
>> +out:
>>         if (err && err != -EBADMSG)
>>                 return err;
>>
>> --
>> 2.25.1
>>

Re: [PATCH] mmc: core: Improve fallback to speed modes if eMMC HS200 fails

[Ulf Hansson]

On Mon, 14 Mar 2022 at 23:02, Heiner Kallweit <hkallweit1@gmail.com> wrote:
>
> On 14.03.2022 11:54, Ulf Hansson wrote:
> > On Thu, 3 Mar 2022 at 17:45, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> >>
> >> In the error path of mmc_select_hs200() we are trying our best to restore
> >> the card/host into a valid state. This makes sense, especially if we
> >> encounter a simple switch error (-EBADMSG). However, rather than then
> >> continue with using the legacy speed mode, let's try the other better speed
> >> modes first. Additionally, let's update the card->mmc_avail_type to avoid
> >> us from trying a broken HS200 mode again.
> >>
> >> In an Amlogic S905W based TV box where the switch to HS200 mode fails for
> >> the eMMC, this allows us to use the eMMC in DDR mode in favor of the legacy
> >> mode, which greatly improves the performance.
> >>
> >> Suggested-by: Heiner Kallweit <hkallweit1@gmail.com>
> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> >
> > Heiner, does this solve your problems? Can you perhaps run some tests
> > at your side to see how it works for you?
> >
>
> Tested-by: Heiner Kallweit <hkallweit1@gmail.com>

Thanks! Patch applied for next.

[...]

Kind regards
Uffe