| Message ID | 1452842844-16256-1-git-send-email-leoyang.li@nxp.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Jan 15, 2016 at 3:53 PM, Uwe Kleine-König <u.kleine-koenig@pengutronix.de> wrote: > Hello, > > On Fri, Jan 15, 2016 at 01:27:24AM -0600, Li Yang wrote: >> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c >> index a2b132c..1239bfa 100644 >> --- a/drivers/i2c/busses/i2c-imx.c >> +++ b/drivers/i2c/busses/i2c-imx.c >> @@ -1081,8 +1081,11 @@ static int i2c_imx_probe(struct platform_device *pdev) >> return ret; >> } >> >> + /* optional bus recovery feature through pinctrl */ >> i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev); >> - if (IS_ERR(i2c_imx->pinctrl)) { >> + /* bailout on -ENOMEM or -EPROBE_DEFER, continue for other errors */ >> + if (PTR_ERR(i2c_imx->pinctrl) == -ENOMEM || >> + PTR_ERR(i2c_imx->pinctrl) == -EPROBE_DEFER) { >> ret = PTR_ERR(i2c_imx->pinctrl); >> goto clk_disable; >> } >> @@ -1125,7 +1128,10 @@ static int i2c_imx_probe(struct platform_device *pdev) >> i2c_imx, IMX_I2C_I2CR); >> imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR); >> >> - i2c_imx_init_recovery_info(i2c_imx, pdev); >> + if (IS_ERR_OR_NULL(i2c_imx->pinctrl)) > > I'd prefer to set i2c_imx->pinctrl to NULL if it's not used and then use > > if (!i2c_imx->pinctrl) > > here. (Or maybe make i2c_imx_init_recovery_info aware of this situation > to keep the caller simple?) Setting not used pointer to NULL might be a good coding practice generally. But in this case neither the driver nor gpio framework checks if the pinctrl is NULL before accessing it. We still need the driver to make sure pinctrl is not used in this situation. The benefit of the proposed change seems to be pretty limited. :) Regards, Leo -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello Li, On Fri, Jan 15, 2016 at 04:46:06PM +0800, Li Yang wrote: > On Fri, Jan 15, 2016 at 3:53 PM, Uwe Kleine-König > <u.kleine-koenig@pengutronix.de> wrote: > >> - i2c_imx_init_recovery_info(i2c_imx, pdev); > >> + if (IS_ERR_OR_NULL(i2c_imx->pinctrl)) > > > > I'd prefer to set i2c_imx->pinctrl to NULL if it's not used and then use > > > > if (!i2c_imx->pinctrl) > > > > here. (Or maybe make i2c_imx_init_recovery_info aware of this situation > > to keep the caller simple?) > > Setting not used pointer to NULL might be a good coding practice > generally. But in this case neither the driver nor gpio framework > checks if the pinctrl is NULL before accessing it. We still need the > driver to make sure pinctrl is not used in this situation. The > benefit of the proposed change seems to be pretty limited. :) At least it gets rid of IS_ERR_OR_NULL which is used wrongly more often than not. Best regards Uwe
On Fri, Jan 15, 2016 at 5:03 PM, Uwe Kleine-König <u.kleine-koenig@pengutronix.de> wrote: > Hello Li, > > On Fri, Jan 15, 2016 at 04:46:06PM +0800, Li Yang wrote: >> On Fri, Jan 15, 2016 at 3:53 PM, Uwe Kleine-König >> <u.kleine-koenig@pengutronix.de> wrote: >> >> - i2c_imx_init_recovery_info(i2c_imx, pdev); >> >> + if (IS_ERR_OR_NULL(i2c_imx->pinctrl)) >> > >> > I'd prefer to set i2c_imx->pinctrl to NULL if it's not used and then use >> > >> > if (!i2c_imx->pinctrl) >> > >> > here. (Or maybe make i2c_imx_init_recovery_info aware of this situation >> > to keep the caller simple?) >> >> Setting not used pointer to NULL might be a good coding practice >> generally. But in this case neither the driver nor gpio framework >> checks if the pinctrl is NULL before accessing it. We still need the >> driver to make sure pinctrl is not used in this situation. The >> benefit of the proposed change seems to be pretty limited. :) > > At least it gets rid of IS_ERR_OR_NULL which is used wrongly more often > than not. It's true that this API is not used a lot. Are you suggesting that it is poorly designed and probably should be removed? But I still don't quite get the point why it tends to be wrongly used. Do you consider the use in this patch a wrongly used case? Regards, Leo -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello Leo, On Mon, Jan 18, 2016 at 04:22:51PM +0800, Li Yang wrote: > On Fri, Jan 15, 2016 at 5:03 PM, Uwe Kleine-König > <u.kleine-koenig@pengutronix.de> wrote: > > On Fri, Jan 15, 2016 at 04:46:06PM +0800, Li Yang wrote: > >> On Fri, Jan 15, 2016 at 3:53 PM, Uwe Kleine-König > >> <u.kleine-koenig@pengutronix.de> wrote: > >> >> - i2c_imx_init_recovery_info(i2c_imx, pdev); > >> >> + if (IS_ERR_OR_NULL(i2c_imx->pinctrl)) > >> > > >> > I'd prefer to set i2c_imx->pinctrl to NULL if it's not used and then use > >> > > >> > if (!i2c_imx->pinctrl) > >> > > >> > here. (Or maybe make i2c_imx_init_recovery_info aware of this situation > >> > to keep the caller simple?) > >> > >> Setting not used pointer to NULL might be a good coding practice > >> generally. But in this case neither the driver nor gpio framework > >> checks if the pinctrl is NULL before accessing it. We still need the > >> driver to make sure pinctrl is not used in this situation. The > >> benefit of the proposed change seems to be pretty limited. :) > > > > At least it gets rid of IS_ERR_OR_NULL which is used wrongly more often > > than not. > > It's true that this API is not used a lot. Are you suggesting that it > is poorly designed and probably should be removed? But I still don't > quite get the point why it tends to be wrongly used. Do you consider > the use in this patch a wrongly used case? See http://permalink.gmane.org/gmane.linux.ports.arm.omap/97874 for an earlier discussion. Having said that, I think at the moment there is no such bug in this case, still I agree with Russell that IS_ERR_OR_NULL isn't nice and so would prefer not to add new instances. Best regards Uwe
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index a2b132c..1239bfa 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -1081,8 +1081,11 @@ static int i2c_imx_probe(struct platform_device *pdev) return ret; } + /* optional bus recovery feature through pinctrl */ i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev); - if (IS_ERR(i2c_imx->pinctrl)) { + /* bailout on -ENOMEM or -EPROBE_DEFER, continue for other errors */ + if (PTR_ERR(i2c_imx->pinctrl) == -ENOMEM || + PTR_ERR(i2c_imx->pinctrl) == -EPROBE_DEFER) { ret = PTR_ERR(i2c_imx->pinctrl); goto clk_disable; } @@ -1125,7 +1128,10 @@ static int i2c_imx_probe(struct platform_device *pdev) i2c_imx, IMX_I2C_I2CR); imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR); - i2c_imx_init_recovery_info(i2c_imx, pdev); + if (IS_ERR_OR_NULL(i2c_imx->pinctrl)) + dev_info(&pdev->dev, "can't get pinctrl, bus recovery feature disabled\n"); + else + i2c_imx_init_recovery_info(i2c_imx, pdev); /* Add I2C adapter */ ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
Since commit 1c4b6c3bcf30 ("i2c: imx: implement bus recovery") the driver starts to use gpio/pinctrl to do i2c bus recovery. But pinctrl is not always available for platforms using this driver such as ls1021a and ls1043a, and the device tree binding also mentioned this gpio based recovery mechanism as optional. The patch make it really optional that the probe function won't bailout when pinctrl is not available and it won't try to register recovery functions if pinctrl is NULL when the PINCTRL is not enabled at all. Signed-off-by: Li Yang <leoyang.li@nxp.com> Cc: Gao Pan <pandy.gao@nxp.com> Acked-by: Linus Walleij <linus.walleij@linaro.org> --- v3: Rebased to Wolfram's for-next branch Added acked-by from Linus Walleij Update to use new nxp email addresses due to company merge drivers/i2c/busses/i2c-imx.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)