From: <Codrin.Ciubotariu@microchip.com>
To: <michael@walle.cc>
Cc: alexandre.belloni@bootlin.com, linux-kernel@vger.kernel.org,
Nicolas.Ferre@microchip.com, dri-devel@lists.freedesktop.org,
sumit.semwal@linaro.org, linaro-mm-sig@lists.linaro.org,
linux-i2c@vger.kernel.org, stable@vger.kernel.org,
Claudiu.Beznea@microchip.com, christian.koenig@amd.com,
linux-arm-kernel@lists.infradead.org,
linux-media@vger.kernel.org
Subject: Re: [PATCH] i2c: at91: use dma safe buffers
Date: Tue, 5 Apr 2022 13:58:20 +0000 [thread overview]
Message-ID: <74494dda-e0cd-aa73-7e58-e4359c1ba292@microchip.com> (raw)
In-Reply-To: <27f124c9adaf8a4fbdfb7a38456c4a2e@walle.cc>
On 05.04.2022 14:09, Michael Walle wrote:
> Am 2022-04-05 12:02, schrieb Codrin.Ciubotariu@microchip.com:
>> On 05.04.2022 12:38, Michael Walle wrote:
>>> Am 2022-04-05 11:23, schrieb Codrin.Ciubotariu@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().
at91_twi_read_data_dma_callback() is called as callback if
dma_async_issue_pending(dma->chan_rx) is called.
dma_async_issue_pending(dma->chan_rx) is called on
at91_twi_read_data_dma(), which is called in at91_do_twi_transfer(),
which we decided above to skip in case of error.
next prev parent reply other threads:[~2022-04-06 8:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-03 16:17 [PATCH] i2c: at91: use dma safe buffers Michael Walle
2022-03-04 7:35 ` Christian König
2022-03-04 8:04 ` Wolfram Sang
2022-03-04 8:10 ` Christian König
2022-03-04 8:43 ` Wolfram Sang
2022-03-04 8:54 ` Christian König
2022-03-28 7:35 ` Michael Walle
2022-04-05 9:23 ` Codrin.Ciubotariu
2022-04-05 9:38 ` Michael Walle
2022-04-05 10:02 ` Codrin.Ciubotariu
2022-04-05 11:09 ` Michael Walle
2022-04-05 13:58 ` Codrin.Ciubotariu [this message]
2022-04-05 14:08 ` Michael Walle
2022-04-07 11:50 ` Codrin.Ciubotariu
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