linux-kernel - Re: [PATCH v2 2/2] i2c: lpi2c: Use cleanup helper for dma_async_tx

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Message-ID: <3a065c54-f043-4c94-ac52-ef5b48a0dc71@intel.com>
Date: Thu, 4 Dec 2025 08:09:12 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Frank Li <Frank.li@....com>
Cc: Vinod Koul <vkoul@...nel.org>, Dong Aisheng <aisheng.dong@....com>,
 Andi Shyti <andi.shyti@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
 Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, dmaengine@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 carlos.song@....com
Subject: Re: [PATCH v2 2/2] i2c: lpi2c: Use cleanup helper for
 dma_async_tx_descriptor error handling



On 12/3/25 6:27 PM, Frank Li wrote:
> On Wed, Dec 03, 2025 at 03:52:09PM -0700, Dave Jiang wrote:
>>
>>
>> On 10/3/25 9:26 AM, Frank Li wrote:
>>> Use the cleanup helper to simplify dma_async_tx_descriptor error handling.
>>>
>>> No functional change.
>>>
>>> Signed-off-by: Frank Li <Frank.Li@....com>
>>> ---
>>> change v2
>>>  need goto unmap buffer.
>>>
>>> desc_prepare_err_exit:
>>>         dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>>>                          dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>>>         return -EINVAL;
>>>
>>> submit_err_exit:
>>>         dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>>>                          dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>>>         dmaengine_desc_free(rx_cmd_desc)
>>>
>>> auto cleanup by __free, so whole error path submit_err_exit can be removed
>>> and use desc_prepare_err_exit label.
>>> ---
>>>  drivers/i2c/busses/i2c-imx-lpi2c.c | 11 +++--------
>>>  1 file changed, 3 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
>>> index 03b5a7e8c361abe1d75fb4d31f9614bbc6387d93..e31c2d81f59f18a09d34f79896a7fa4bb83c0a12 100644
>>> --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
>>> +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
>>> @@ -722,7 +722,7 @@ static void lpi2c_dma_callback(void *data)
>>>
>>>  static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
>>>  {
>>> -	struct dma_async_tx_descriptor *rx_cmd_desc;
>>> +	struct dma_async_tx_descriptor *rx_cmd_desc __free(dma_async_tx_descriptor) = NULL;
>>>  	struct lpi2c_imx_dma *dma = lpi2c_imx->dma;
>>>  	struct dma_chan *txchan = dma->chan_tx;
>>>  	dma_cookie_t cookie;
>>> @@ -746,10 +746,11 @@ static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
>>>  	cookie = dmaengine_submit(rx_cmd_desc);
>>>  	if (dma_submit_error(cookie)) {
>>>  		dev_err(&lpi2c_imx->adapter.dev, "submitting DMA failed, use pio\n");
>>> -		goto submit_err_exit;
>>> +		goto desc_prepare_err_exit;
>>
>> Typically if you are introducing cleanup usage, you will want to remove all the goto usages. Otherwise it gets kinda messy having both styles. Although not sure how to do a cleanup macro with dma_unmap_*. Unless a local one where lpi2c_imx_dma also contains a ptr to the device. Then that may be doable.
> 
> dma_unmap() patch at
> https://lore.kernel.org/imx/aPZbuY5bLpkoO2J%2F@lizhi-Precision-Tower-5810/
> 
> The first patch need be pickup and dma umap firstly.  Then I can remove all
> goto.

perfect


> 
> Frank
> 
>>
>> DJ>  	}
>>>
>>>  	dma_async_issue_pending(txchan);
>>> +	retain_and_null_ptr(rx_cmd_desc);
>>>
>>>  	return 0;
>>>
>>> @@ -757,12 +758,6 @@ static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
>>>  	dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>>>  			 dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>>>  	return -EINVAL;
>>> -
>>> -submit_err_exit:
>>> -	dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>>> -			 dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>>> -	dmaengine_desc_free(rx_cmd_desc);
>>> -	return -EINVAL;
>>>  }
>>>
>>>  static int lpi2c_dma_submit(struct lpi2c_imx_struct *lpi2c_imx)
>>>
>>
>