Re: [PATCH] gpu: host1x: Do not setup DMA for virtual devices

Jon Hunter
2024-04-03T10:07:55Z

Hi Thierry,

On 15/03/2024 11:25, Jon Hunter wrote:
>
> On 14/03/2024 15:49, Thierry Reding wrote:
>> From: Thierry Reding <treding@nvidia.com>
>>
>> The host1x devices are virtual compound devices and do not perform DMA
>> accesses themselves, so they do not need to be set up for DMA.
>>
>> Ideally we would also not need to set up DMA masks for the virtual
>> devices, but we currently still need those for legacy support on old
>> hardware.
>>
>> Signed-off-by: Thierry Reding <treding@nvidia.com>
>> ---
>>   drivers/gpu/host1x/bus.c | 8 --------
>>   1 file changed, 8 deletions(-)
>>
>> diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
>> index 783975d1384f..7c52757a89db 100644
>> --- a/drivers/gpu/host1x/bus.c
>> +++ b/drivers/gpu/host1x/bus.c
>> @@ -351,11 +351,6 @@ static int host1x_device_uevent(const struct
>> device *dev,
>>       return 0;
>>   }
>> -static int host1x_dma_configure(struct device *dev)
>> -{
>> -    return of_dma_configure(dev, dev->of_node, true);
>> -}
>> -
>>   static const struct dev_pm_ops host1x_device_pm_ops = {
>>       .suspend = pm_generic_suspend,
>>       .resume = pm_generic_resume,
>> @@ -369,7 +364,6 @@ const struct bus_type host1x_bus_type = {
>>       .name = "host1x",
>>       .match = host1x_device_match,
>>       .uevent = host1x_device_uevent,
>> -    .dma_configure = host1x_dma_configure,
>>       .pm = &host1x_device_pm_ops,
>>   };
>> @@ -458,8 +452,6 @@ static int host1x_device_add(struct host1x *host1x,
>>       device->dev.bus = &host1x_bus_type;
>>       device->dev.parent = host1x->dev;
>> -    of_dma_configure(&device->dev, host1x->dev->of_node, true);
>> -
>>       device->dev.dma_parms = &device->dma_parms;
>>       dma_set_max_seg_size(&device->dev, UINT_MAX);
>
>
> Tested-by: Jon Hunter <jonathanh@nvidia.com>
> Acked-by: Jon Hunter <jonathanh@nvidia.com>

I don't see this in -next yet?

Ideally, if we don't see any issues with this we should pull this into
v6.8.y stable branch because I am now seeing the warning there. Should
we apply a fixes tag to this?

Thanks
Jon

--
nvpublic