On 12/03/2015 05:32 PM, Arnd Bergmann wrote:
> On Thursday 03 December 2015 16:33:11 Peter Ujfalusi wrote:
>> +
>> +/**
>> + * dma_request_chan - try to allocate an exclusive slave channel
>> + * @dev: pointer to client device structure
>> + * @name: slave channel name
>> + *
>> + * Returns pointer to appropriate DMA channel on success or an error pointer.
>> + */
>> +struct dma_chan *dma_request_chan(struct device *dev, const char *name)
>> +{
>> + struct dma_device *d, *_d;
>> + struct dma_chan *chan = NULL;
>> +
>> + /* If device-tree is present get slave info from here */
>> + if (dev->of_node)
>> + chan = of_dma_request_slave_channel(dev->of_node, name);
>> +
>> + /* If device was enumerated by ACPI get slave info from here */
>> + if (has_acpi_companion(dev) && !chan)
>> + chan = acpi_dma_request_slave_chan_by_name(dev, name);
>
> I just noticed that you are creating this as a new interface, rather than
> changing dma_request_slave_channel_reason() and making the old interface
> a static inline wrapper. What is the reasoning behind that?
Oh, it was in my plans. Will do it for v02
> I think if we make both interfaces do the same thing, it's easier
> to do the migration.
>
>> + if (chan) {
>> + /* Valid channel found */
>> + if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
>> + return chan;
>> +
>> + pr_warn("%s: %s DMA request failed, falling back to legacy\n",
>> + __func__, dev->of_node ? "OF" : "ACPI");
>> + }
>
> Maybe print the error code as well?
Or remove the print altogether?
In a healthy system we will either get the channel or the EPROBE_DEFER, in
case of the platforms where the DT lookup does not work we expect errors and
it is 'normal'.
I think if we fail via DT/ACPI and we fail with legacy also then the client
driver will say something about it anyways, or deal with it as it see fits.
--
Péter
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