[PATCH] mci: dw_mmc: set dma mask to work correctly on 64bit platforms
a.fatoum at pengutronix.de
Fri Jun 11 03:40:12 PDT 2021
On 11.06.21 12:02, Sascha Hauer wrote:
> On Fri, Jun 11, 2021 at 10:23:25AM +0200, Ahmad Fatoum wrote:
>> Hello Sascha,
>> On 10.06.21 15:10, Sascha Hauer wrote:
>>> The variant we support currently can only do 32bit DMA. Adjust dma mask
>>> accordingly. Also use dma_map_single() rather than dma_sync_single() to
>>> actually get errors when the mapping fails.
>>> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
>> Tested-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
>> On a StarFive JH7100 (64-bit CPU, 32-bit MMC controller, non-1:1 mapping for
>> coherent DMA).
>>> host->idmac = dma_alloc_coherent(sizeof(*host->idmac) * DW_MMC_NUM_IDMACS,
>>> - DMA_ADDRESS_BROKEN);
>>> + &host->idmac_dma);
>>> + if (!host->idmac)
>> That works for Linux, but not for barebox: barebox dma_alloc_coherent doesn't have
>> a dev parameter, so it can't check for dma_mapping_error() internally.
> Yeah, I know. I have that on my mental todo list and hoped nobody would
Tss. tss. ;)
> Adding a dev parameter to dma_alloc_coherent() is one thing. With that
> we can check for errors. The next step of course would be to allocate
> memory in the allowed area, not only to complain.
What you can do for now is checking for dma_mapping_error here and abort
the probe if you exceed the mask.
>> dma_alloc_coherent also never returns NULL in barebox, all implementations, except
>> for kvx, abort if no memory could be allocated.
>>> + return PTR_ERR(-ENOMEM);
>> -ENOMEM is no pointer.
> Yes, fixed.
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