linux-kernel - Re: [PATCH v5] i2c: imx: support DMA defer probing

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Message-ID: <Z2QQI2gJNLjI-fam@pengutronix.de>
Date: Thu, 19 Dec 2024 13:22:59 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Andi Shyti <andi.shyti@...nel.org>
Cc: Carlos Song <carlos.song@....com>, frank.li@....com,
	kernel@...gutronix.de, shawnguo@...nel.org, s.hauer@...gutronix.de,
	festevam@...il.com, linux-i2c@...r.kernel.org, imx@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Clark Wang <xiaoning.wang@....com>,
	Ahmad Fatoum <a.fatoum@...gutronix.de>
Subject: Re: [PATCH v5] i2c: imx: support DMA defer probing

On Thu, Dec 19, 2024 at 01:02:29PM +0100, Andi Shyti wrote:
> Hi Carlos,
> 
> > +	/*
> > +	 * Init DMA config if supported, -ENODEV means DMA not enabled at
> > +	 * this platform, that is not a real error, so just remind "only
> > +	 * PIO mode is used". If DMA is enabled, but meet error when request
> > +	 * DMA channel, error should be showed in probe error log. PIO mode
> > +	 * should be available regardless of DMA.
> > +	 */
> > +	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> > +	if (ret) {
> > +		if (ret == -EPROBE_DEFER)
> > +			goto clk_notifier_unregister;
> > +		else if (ret == -ENODEV)
> > +			dev_dbg(&pdev->dev, "Only use PIO mode\n");
> > +		else
> > +			dev_err_probe(&pdev->dev, ret, "Failed to setup DMA, only use PIO mode\n");
> 
> Just for understanding, should we quit in this last case, as
> well?
> 
> Before we were ignoring ENODEV and EPROBE_DEFER, but now you are
> making it clear that other failures like ENOMEM might happen.

Good point, dev_err_probe() would not print an error in case of EPROBE_DEFER,
but in this case we should only print error and continue with PIO.

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