[PATCH] mmc: meson-gx: work around broken SDIO with certain WiFi chips

[hkallweit1@gmail.com (Heiner Kallweit)]

Am 08.06.2017 um 08:56 schrieb Ulf Hansson:
> On 8 June 2017 at 07:56, Heiner Kallweit <hkallweit1@gmail.com> wrote:
>> There have been reports about SDIO failing with certain WiFi chips in
>> descriptor chain mode. SD / eMMC are working fine.
>>
>> So let's fall back to bounce buffer mode for command SD_IO_RW_EXTENDED.
>> This was reported to fix this error.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> 
> Is this material for stable? What commit does it fix?
> 
> Please resend to linux-mmc.
> 
Sorry, will re-send with the missing information.

Rgds, Heiner


> Kind regards
> Uffe
> 
>> ---
>>  drivers/mmc/host/meson-gx-mmc.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index 1842ed34..4cdbe3c0 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -210,6 +210,15 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
>>         int i;
>>         bool use_desc_chain_mode = true;
>>
>> +       /*
>> +        * Broken SDIO with AP6335-based WiFi on Khadas VIM Pro has been
>> +        * reported. For some strange reason this occurs in descriptor
>> +        * chain mode only. So let's fall back to bounce buffer mode
>> +        * for command SD_IO_RW_EXTENDED.
>> +        */
>> +       if (mrq->cmd->opcode == SD_IO_RW_EXTENDED)
>> +               return;
>> +
>>         for_each_sg(data->sg, sg, data->sg_len, i)
>>                 /* check for 8 byte alignment */
>>                 if (sg->offset & 7) {
>> --
>> 2.13.0
>>
>