[PATCH] i2c: at91: use dma safe buffers
Michael Walle
michael at walle.cc
Tue Apr 5 11:09:04 UTC 2022
Am 2022-04-05 12:02, schrieb Codrin.Ciubotariu at microchip.com:
> On 05.04.2022 12:38, Michael Walle wrote:
>> Am 2022-04-05 11:23, schrieb Codrin.Ciubotariu at microchip.com:
>>>> + if (dev->use_dma) {
>>>> + dma_buf = i2c_get_dma_safe_msg_buf(m_start, 1);
>>>
>>> If you want, you could just dev->buf = i2c_get_dma_safe...
>>
>> But where is the error handling in that case? dev->buf will
>> be NULL, which is eventually passed to dma_map_single().
>>
>> Also, I need the dma_buf for the i2c_put_dma_safe_msg_buf()
>> call anyway, because dev->buf will be modified during
>> processing.
>
> You still:
> if (!dev->buf) {
> ret = -ENOMEM;
> goto out;
> }
>
> So, at91_do_twi_transfer()/dma_map_single() will not be called.
Ahh, I misunderstood you. Yes, but as I said, I need the dma_buf
temporary variable anyway, because dev->buf is modified, eg. see
at91_twi_read_data_dma_callback().
-michael
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