[PATCH 2/3] ARM: SAMSUNG: Modify pl330 channel filter function

[Thomas Abraham]

Hi Russell,

On 23 August 2011 03:22, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Tue, Aug 23, 2011 at 03:29:44AM +0530, Thomas Abraham wrote:
>> With the change in dma channels private data information, the pl330
>> channel filter function is modified to look for a simple u8 value
>> instead of the now unused 'struct dma_pl330_peri' value.
>>
>> Signed-off-by: Thomas Abraham <thomas.abraham at linaro.org>
>> ---
>>  arch/arm/plat-samsung/dma-ops.c |    4 ++--
>>  1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/plat-samsung/dma-ops.c b/arch/arm/plat-samsung/dma-ops.c
>> index 6e3d9ab..4f1430b 100644
>> --- a/arch/arm/plat-samsung/dma-ops.c
>> +++ b/arch/arm/plat-samsung/dma-ops.c
>> @@ -19,8 +19,8 @@
>>
>>  static inline bool pl330_filter(struct dma_chan *chan, void *param)
>>  {
>> -     struct dma_pl330_peri *peri = chan->private;
>> -     return peri->peri_id == (unsigned)param;
>> +     u8 *peri_id = chan->private;
>> +     return *peri_id == (unsigned)param;
>>  }
>
> As a word of warning - this will fail horribly if you have mixed DMA
> engines in the system.  While we wait for a better scheme, we really
> need to sort out these filter functions properly and stop poking
> about in data which may not be what we expect.
>
> One solution to that is to move pl330_filter() into drivers/dma/pl330.c
> and have it check chan->device->dev->driver == &pl330_driver.driver
> _before_ we start accessing chan->private.
>
> That's not a comment against your patch - you're not really changing
> the brokenness of this function.  It would be good to see a follow up
> patch fixing it properly though.
>

Ok. I will prepare a patch to move the pl330_filter function into
drivers/dma/pl330.c and also add the check that you have proposed.

Thanks for your help.

Regards,
Thomas.