[PATCH] mmc: meson-gx: set max block count to 256

[Heiner Kallweit]

Am 27.01.2017 um 19:28 schrieb Kevin Hilman:
> Heiner Kallweit <hkallweit1 at gmail.com> writes:
> 
>> So far max_blk_count isn't set what results in a default of value 8
>> to be used (PAGE_SIZE / block size).
>>
>> Set max_blk_count to 256 as used in the uboot driver.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
> 
> Thanks for the patch. A minor comment below:
> 
>> ---
>>  drivers/mmc/host/meson-gx-mmc.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
>> index 3308b5b6..030425be 100644
>> --- a/drivers/mmc/host/meson-gx-mmc.c
>> +++ b/drivers/mmc/host/meson-gx-mmc.c
>> @@ -799,6 +799,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
>>  		goto free_host;
>>  	}
>>  
>> +	mmc->max_blk_count = 256;
> 
> A step in the right direction, but the # blocks is actually a 9-bit
> field (c.f. length field of cmd_cfg part of descriptor (bits 8:0).
> 
> So this should be more like:
> 
> 	/* blk count is 'length' field of cmd_cfg part of descriptor */
> 	mmc->max_blk_count = CMD_CFG_LENGTH_MASK + 1;
> 
> I tested that change locally, so after changing that, please resend and
> feel free to add:
> 
max_blk_count = 0 means unlimited number of blocks. Therefore I think
we have to go with: mmc->max_blk_count = CMD_CFG_LENGTH_MASK
And I figured out later that we also have to set mmc->max_req_size.

In my tests the system never read / wrote more than 8 blocks in a row,
most likely because the upper block layers use 4k blocks.

Therefore setting max_blk_count doesn't really provide a benefit but
I think it's cleaner to expose the actual chip limit.

Rgds, Heiner

> Reviewed-by: Kevin Hilman <khilman at baylibre.com>
> Tested-by: Kevin Hilman <khilman at baylibre.com>
> 
> Kevin
>