[U-Boot] [PATCH] mmc: dw_mmc: Round up descriptor end to nearest multiple of cacheline size

[Marek Vasut]

On 3/30/19 10:18 PM, Simon Glass wrote:
> Hi Marek,
> 
> On Sat, 23 Mar 2019 at 11:55, Marek Vasut <marex at denx.de> wrote:
>>
>> The driver currently calculates the end address of cache flush operation
>> for the DMA descriptors by adding cacheline size to the start address of
>> the last DMA descriptor. This is not safe, as the cacheline size may be,
>> in some unlikely cases, smaller than the DMA descriptor size. Replace the
>> addition with roundup() applied on the end address of the last DMA
>> descriptor to round it up to the nearest cacheline size multiple.
>>
>> Signed-off-by: Marek Vasut <marex at denx.de>
>> Cc: Jaehoon Chung <jh80.chung at samsung.com>
>> Cc: Simon Glass <sjg at chromium.org>
>> ---
>>  drivers/mmc/dw_mmc.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
>> index 72570235cb..bec30b1479 100644
>> --- a/drivers/mmc/dw_mmc.c
>> +++ b/drivers/mmc/dw_mmc.c
>> @@ -74,15 +74,15 @@ static void dwmci_prepare_data(struct dwmci_host *host,
>>                 dwmci_set_idma_desc(cur_idmac, flags, cnt,
>>                                     (ulong)bounce_buffer + (i * PAGE_SIZE));
>>
>> +               cur_idmac++;
> 
> What is this change for? I don't see it mentioned above.

AFAIR you need to increment the pointer to cur_idmac before breaking out
of the loop, otherwise data_end might point a bit before the actual end
of the buffer.

>>                 if (blk_cnt <= 8)
>>                         break;
>>                 blk_cnt -= 8;
>> -               cur_idmac++;
>>                 i++;
>>         } while(1);
>>
>>         data_end = (ulong)cur_idmac;
>> -       flush_dcache_range(data_start, data_end + ARCH_DMA_MINALIGN);
>> +       flush_dcache_range(data_start, roundup(data_end, ARCH_DMA_MINALIGN));
>>
>>         ctrl = dwmci_readl(host, DWMCI_CTRL);
>>         ctrl |= DWMCI_IDMAC_EN | DWMCI_DMA_EN;
>> --
>> 2.20.1
>>
> 
> Regards,
> Simon
> 


-- 
Best regards,
Marek Vasut