From: Michael Walle <michael@walle.cc>
To: Codrin.Ciubotariu@microchip.com
Cc: Nicolas.Ferre@microchip.com, alexandre.belloni@bootlin.com,
Claudiu.Beznea@microchip.com, sumit.semwal@linaro.org,
christian.koenig@amd.com, linux-i2c@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
stable@vger.kernel.org
Subject: Re: [PATCH] i2c: at91: use dma safe buffers
Date: Tue, 05 Apr 2022 13:09:04 +0200 [thread overview]
Message-ID: <27f124c9adaf8a4fbdfb7a38456c4a2e@walle.cc> (raw)
In-Reply-To: <360914ee-594c-86bc-2436-aa863a67953a@microchip.com>
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().
-michael
next prev parent reply other threads:[~2022-04-05 20:56 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 [this message]
2022-04-05 13:58 ` Codrin.Ciubotariu
2022-04-05 14:08 ` Michael Walle
2022-04-07 11:50 ` Codrin.Ciubotariu
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