On 23/05/2017 08:58, Ulf Hansson wrote:
> On 22 May 2017 at 11:09, Phil Elwell <phil@xxxxxxxxxxxxxxx> wrote:
>> since:
>> commit 0589342c27944e50ebd7a54f5215002b6598b748
>> Author: Rob Herring <rob.herring@xxxxxxxxxxx>
>> Date: Tue Oct 29 23:36:46 2013 -0500
>>
>> of: set dma_mask to point to coherent_dma_mask
>>
>> Platform devices created by DT code don't initialize dma_mask pointer to
>> anything. Set it to coherent_dma_mask by default if the architecture
>> code has not set it.
>>
>> the mmc-spi driver no longer detects the sd-cards any longer.
>>
>> This patch disables the offending section in mmc_spi
>> so that the driver works again and detects the sd card normally.
>>
>> There is no real negative impact as the spi-framework
>> does no longer rely on driver-provided DMA mappings but
>> maps the transfers transparently.
>>
>> Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
>> Submitted-by: Phil Elwell <phil@xxxxxxxxxxxxxxx>
>> ---
>> drivers/mmc/host/mmc_spi.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
>> index ae19d83bb9de0..16946e2513afa 100644
>> --- a/drivers/mmc/host/mmc_spi.c
>> +++ b/drivers/mmc/host/mmc_spi.c
>> @@ -1387,6 +1387,16 @@ static int mmc_spi_probe(struct spi_device *spi)
>> if (!host->data)
>> goto fail_nobuf1;
>>
>> + /* for some reason mmc_spi does not work with this enabled
>> + * it is not needed anyway, as the SPI framework does DMA
>> + * transfers now automatically
>> + * the patch that introduced this was:
>> + * commit 0589342c27944e50ebd7a54f5215002b6598b748
>> + * Author: Rob Herring <rob.herring@xxxxxxxxxxx>
>> + * Date: Tue Oct 29 23:36:46 2013 -0500
>> + * of: set dma_mask to point to coherent_dma_mask
>> + */
>> +#if 0
>> if (spi->master->dev.parent->dma_mask) {
>> struct device *dev = spi->master->dev.parent;
>>
>> @@ -1402,6 +1412,7 @@ static int mmc_spi_probe(struct spi_device *spi)
>> host->data_dma, sizeof(*host->data),
>> DMA_BIDIRECTIONAL);
>> }
>> +#endif
>>
>> /* setup message for status/busy readback */
>> spi_message_init(&host->readback);
>
> Phil, I am not sure how to go with this.
>
> Your change drops the dma implementation in the mmc_spi driver as
> host->dma_dev now never gets assigned. I do think that makes sense as
> the dma support should be implemented in the spi master driver and not
> in the spi client driver, which currently is the case for mmc_spi.
>
> Then perhaps a more proper change would be to remove the dma
> implementation in mmc_spi altogether?
I don't have enough in-depth SPI knowledge to make that decision - I'm happy to go
with what the SPI experts recommend.
> And one more thing, next time also cc the spi-list and Mark Brown, to
> try to some broader input.
Thanks for the tip, Ulf - I just went with what scripts/get_maintainer.pl suggested.
Perhaps that list needs to be updated?
Phil
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