Re: [PATCH v2] ata: pata_pxa: handle failure of devm_ioremap()

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 6/13/22 03:37, Sergei Shtylyov wrote:
> On 6/12/22 3:57 PM, Li Qiong wrote:
> 
>> As the possible failure of the devm_ioremap(), the return value
>> could be NULL. Therefore it should be better to check it and
>> print error message, return '-ENOMEM' error code.

This error is very unlikely. So unless you are seeing actual problems in
the field, I do not think it is worth fixing.

>>
>> Signed-off-by: Li Qiong <liqiong@nfschina.com>
>> Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
>> ---
>> v2:
>> - add driver's name (pata_pxa) to subject.
>> ---
>>  drivers/ata/pata_pxa.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/ata/pata_pxa.c b/drivers/ata/pata_pxa.c
>> index 985f42c4fd70..cd1a8f37f920 100644
>> --- a/drivers/ata/pata_pxa.c
>> +++ b/drivers/ata/pata_pxa.c
>> @@ -228,6 +228,11 @@ static int pxa_ata_probe(struct platform_device *pdev)
>>  	ap->ioaddr.bmdma_addr	= devm_ioremap(&pdev->dev, dma_res->start,
>>  						resource_size(dma_res));
> 
>    Looking again into this driver, this statement doesn't make sense: dma_res
> points to a DMA resource, calling devm_ioremap() on it is just wrong... and

Yes, having to do an ioremap of an IORESOURCE_DMA resource is rather
unusual. dmaengine_slave_config() should be doing anything that is
required for that resource.

> 'ap->ioaddr.bmdma_addr' doesn;t seem to be used anyways...

It is used in lbata-sff.c.

A much cleaner fix would be to use
devm_platform_get_and_ioremap_resource() or
devm_platform_ioremap_resource() which will also remove the call to
platform_get_resource((). But as mentioned above, unless this is fixing an
actual bug in production, I do not think this is worth it.

> 
> MBR, Sergey


-- 
Damien Le Moal
Western Digital Research