[PATCH] dma: of-dma: return error when 'dma-cells' not found

[padma.kvr@gmail.com (Padma Venkat)]

On Tue, Mar 5, 2013 at 3:13 PM, Rob Herring <robherring2@gmail.com> wrote:
> On 03/05/2013 03:25 AM, Padmavathi Venna wrote:
>> This patch returns error when 'dma-cells' property not found
>> in the corresponding device node. With out this change there
>> is a crash in the generic dma incompatible platforms.
>>
>> Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
>
> NAK.
>
> #dma-cells should be optional. It is not needed for platforms supporting
> memory to memory transfers only and should therefore be optional. You
> cannot assume the dtb can be updated and kernel changes need to work
> with old dtbs. I've submitted patches to address this and fix the crash:
>
> https://lists.ozlabs.org/pipermail/devicetree-discuss/2013-February/028769.html
>

Okay.

Thanks
Padma

> Rob
>> ---
>>
>> Based on Vinod Koul next branch.
>>
>>  drivers/dma/of-dma.c |    8 +++++++-
>>  1 files changed, 7 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
>> index 69d04d2..46aca0d 100644
>> --- a/drivers/dma/of-dma.c
>> +++ b/drivers/dma/of-dma.c
>> @@ -92,6 +92,7 @@ int of_dma_controller_register(struct device_node *np,
>>                               void *data)
>>  {
>>       struct of_dma   *ofdma;
>> +     const    __be32 *ip;
>>       int             nbcells;
>>
>>       if (!np || !of_dma_xlate) {
>> @@ -103,7 +104,12 @@ int of_dma_controller_register(struct device_node *np,
>>       if (!ofdma)
>>               return -ENOMEM;
>>
>> -     nbcells = be32_to_cpup(of_get_property(np, "#dma-cells", NULL));
>> +     ip = of_get_property(np, "#dma-cells", NULL);
>> +     if (!ip)
>> +             return -ENXIO;
>> +
>> +     nbcells = be32_to_cpup(ip);
>> +
>>       if (!nbcells) {
>>               pr_err("%s: #dma-cells property is missing or invalid\n",
>>                      __func__);
>>
>