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Message-ID:
<AM0PR0402MB3937614F4866F4F15D2FDA21E8282@AM0PR0402MB3937.eurprd04.prod.outlook.com>
Date: Wed, 27 Nov 2024 07:48:13 +0000
From: Carlos Song <carlos.song@....com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
CC: Frank Li <frank.li@....com>, "o.rempel@...gutronix.de"
<o.rempel@...gutronix.de>, "kernel@...gutronix.de" <kernel@...gutronix.de>,
"andi.shyti@...nel.org" <andi.shyti@...nel.org>, "shawnguo@...nel.org"
<shawnguo@...nel.org>, "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>, "linux-i2c@...r.kernel.org"
<linux-i2c@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
Subject: RE: [EXT] Re: [PATCH v3] i2c: imx: support DMA defer probing
> -----Original Message-----
> From: Marc Kleine-Budde <mkl@...gutronix.de>
> Sent: Wednesday, November 27, 2024 3:42 PM
> To: Carlos Song <carlos.song@....com>
> Cc: Frank Li <frank.li@....com>; o.rempel@...gutronix.de;
> kernel@...gutronix.de; andi.shyti@...nel.org; 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
> Subject: [EXT] Re: [PATCH v3] i2c: imx: support DMA defer probing
>
> On 27.11.2024 15:44:58, carlos.song@....com wrote:
> > From: Carlos Song <carlos.song@....com>
> >
> > Return -EPROBE_DEFER when dma_request_slave_channel() because DMA
> > driver have not ready yet.
> >
> > Move i2c_imx_dma_request() before registering I2C adapter to avoid
> > infinite loop of .probe() calls to the same driver, see "e8c220fac415
> > Revert "i2c: imx: improve the error handling in i2c_imx_dma_request()""
> > and "Documentation/driver-api/driver-model/driver.rst".
> >
> > Use CPU mode to avoid stuck registering i2c adapter when DMA resources
> > are unavailable.
> >
> > Signed-off-by: Carlos Song <carlos.song@....com>
> > Signed-off-by: Clark Wang <xiaoning.wang@....com>
> > ---
> > Change for V3:
> > - According to Marc's comment, remove error print when defer probe.
> > Add info log when DMA has not been enabled and add error log when
> > DMA error, both won't stuck the i2c adapter register, just for reminding,
> > i2c adapter is working only in PIO mode.
> > Change for V2:
> > - According to Frank's comments, wrap at 75 char and Simplify fix code
> > at i2c_imx_dma_request().
> > - Use strict patch check, fix alignment warning at
> > i2c_imx_dma_request()
> > ---
> > drivers/i2c/busses/i2c-imx.c | 31 +++++++++++++++++++++++--------
> > 1 file changed, 23 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-imx.c
> > b/drivers/i2c/busses/i2c-imx.c index 5ed4cb61e262..47112a38d034 100644
> > --- a/drivers/i2c/busses/i2c-imx.c
> > +++ b/drivers/i2c/busses/i2c-imx.c
> > @@ -397,17 +397,16 @@ static void i2c_imx_reset_regs(struct
> > imx_i2c_struct *i2c_imx) }
> >
> > /* Functions for DMA support */
> > -static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
> > - dma_addr_t phy_addr)
> > +static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
> > +dma_addr_t phy_addr)
> > {
> > struct imx_i2c_dma *dma;
> > struct dma_slave_config dma_sconfig;
> > - struct device *dev = &i2c_imx->adapter.dev;
> > + struct device *dev = i2c_imx->adapter.dev.parent;
> > int ret;
> >
> > dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
> > if (!dma)
> > - return;
> > + return -ENOMEM;
> >
> > dma->chan_tx = dma_request_chan(dev, "tx");
> > if (IS_ERR(dma->chan_tx)) {
> > @@ -452,7 +451,7 @@ static void i2c_imx_dma_request(struct
> imx_i2c_struct *i2c_imx,
> > dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
> > dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
> >
> > - return;
> > + return 0;
> >
> > fail_rx:
> > dma_release_channel(dma->chan_rx);
> > @@ -460,6 +459,8 @@ static void i2c_imx_dma_request(struct
> imx_i2c_struct *i2c_imx,
> > dma_release_channel(dma->chan_tx);
> > fail_al:
> > devm_kfree(dev, dma);
> > +
> > + return ret;
> > }
> >
> > static void i2c_imx_dma_callback(void *arg) @@ -1803,6 +1804,23 @@
> > static int i2c_imx_probe(struct platform_device *pdev)
> > if (ret == -EPROBE_DEFER)
> > goto clk_notifier_unregister;
> >
> > + /*
> > + * 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_info(&pdev->dev, "Only use PIO mode\n");
>
> On a system without DMA configured, with this patch we now get this info
> message that wasn't there before. I think this might annoy some people, so you
> should remove it.
>
:-) hhh, get it.
How about change to dev_dbg?
> regards,
> Marc
>
> > + else
> > + dev_err_probe(&pdev->dev, ret, "Failed to setup DMA, only use
> PIO mode\n");
> > + }
> > +
> > /* Add I2C adapter */
> > ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
> > if (ret < 0)
> > @@ -1817,9 +1835,6 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
> > i2c_imx->adapter.name);
> > dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
> >
> > - /* Init DMA config if supported */
> > - i2c_imx_dma_request(i2c_imx, phy_addr);
> > -
> > return 0; /* Return OK */
> >
> > clk_notifier_unregister:
> > --
> > 2.34.1
> >
> >
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
> Vertretung Nürnberg | Phone: +49-5121-206917-129 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
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