| Message ID | 20190609055658.3446-1-andrew.smirnov@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | i2c: imx: Initialize DMA before registering I2C adapter | expand |
On Sat, Jun 8, 2019 at 10:57 PM Andrey Smirnov <andrew.smirnov@gmail.com> wrote: > > Allocating DMA after registering I2C adapter can lead to infinite > probing loop, for example, consider the following scenario: > > 1. i2c_imx_probe() is called and successfully registers an I2C > adapter via i2c_add_numbered_adapter() > > 2. As a part of i2c_add_numbered_adapter() new I2C slave devices > are added from DT which results in a call to > driver_deferred_probe_trigger() > > 3. i2c_imx_probe() continues and calls i2c_imx_dma_request() which > due to lack of proper DMA driver returns -EPROBE_DEFER > > 4. i2c_imx_probe() fails, removes I2C adapter and returns > -EPROBE_DEFER, which places it into deferred probe list > > 5. Deferred probe work triggered in #2 above kicks in and calls > i2c_imx_probe() again thus bringing us to step #1 > > To avoid having this problem, move i2c_imx_dma_request() to happen > before i2c_add_numbered_adapter(). > > This problem was encountered on VF610 CFU1 board with > CONFIG_FSL_EDMA=n. > > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> > Cc: Chris Healy <cphealy@gmail.com> > Cc: Wolfram Sang <wsa@the-dreams.de> > Cc: Fabio Estevam <festevam@gmail.com> > Cc: NXP Linux Team <linux-imx@nxp.com> > Cc: linux-i2c@vger.kernel.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org Gentle ping. Any feedback on this? Thanks, Andrey Smirnov
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index b1b8b938d7f4..78a909f56f75 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -278,7 +278,7 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, { 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); @@ -1153,10 +1153,15 @@ static int i2c_imx_probe(struct platform_device *pdev) if (ret == -EPROBE_DEFER) goto clk_notifier_unregister; + /* Init DMA config if supported */ + ret = i2c_imx_dma_request(i2c_imx, phy_addr); + if (ret < 0) + goto clk_notifier_unregister; + /* Add I2C adapter */ ret = i2c_add_numbered_adapter(&i2c_imx->adapter); if (ret < 0) - goto clk_notifier_unregister; + goto dma_free; pm_runtime_mark_last_busy(&pdev->dev); pm_runtime_put_autosuspend(&pdev->dev); @@ -1166,16 +1171,12 @@ static int i2c_imx_probe(struct platform_device *pdev) dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n", i2c_imx->adapter.name); - /* Init DMA config if supported */ - ret = i2c_imx_dma_request(i2c_imx, phy_addr); - if (ret < 0) - goto del_adapter; - dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n"); return 0; /* Return OK */ -del_adapter: - i2c_del_adapter(&i2c_imx->adapter); +dma_free: + if (i2c_imx->dma) + i2c_imx_dma_free(i2c_imx); clk_notifier_unregister: clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb); rpm_disable:
Allocating DMA after registering I2C adapter can lead to infinite probing loop, for example, consider the following scenario: 1. i2c_imx_probe() is called and successfully registers an I2C adapter via i2c_add_numbered_adapter() 2. As a part of i2c_add_numbered_adapter() new I2C slave devices are added from DT which results in a call to driver_deferred_probe_trigger() 3. i2c_imx_probe() continues and calls i2c_imx_dma_request() which due to lack of proper DMA driver returns -EPROBE_DEFER 4. i2c_imx_probe() fails, removes I2C adapter and returns -EPROBE_DEFER, which places it into deferred probe list 5. Deferred probe work triggered in #2 above kicks in and calls i2c_imx_probe() again thus bringing us to step #1 To avoid having this problem, move i2c_imx_dma_request() to happen before i2c_add_numbered_adapter(). This problem was encountered on VF610 CFU1 board with CONFIG_FSL_EDMA=n. Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> Cc: Chris Healy <cphealy@gmail.com> Cc: Wolfram Sang <wsa@the-dreams.de> Cc: Fabio Estevam <festevam@gmail.com> Cc: NXP Linux Team <linux-imx@nxp.com> Cc: linux-i2c@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org --- drivers/i2c/busses/i2c-imx.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-)