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

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Message-ID: <aTDjmdfUk94R3Dyk@lizhi-Precision-Tower-5810>
Date: Wed, 3 Dec 2025 20:27:53 -0500
From: Frank Li <Frank.li@....com>
To: Dave Jiang <dave.jiang@...el.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 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.

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)
> >
>