Hi Linus, Lothar,


On 12/30/2016 05:17 AM, Linus Walleij wrote:

On Thu, Dec 29, 2016 at 11:27 PM, Steve Longerbeam
[off-list ref] wrote:

quoted

Add optional reset-gpios pin control. If present, de-assert the
specified reset gpio pin to bring the chip out of reset.

Signed-off-by: Steve Longerbeam <redacted>
Cc: Linus Walleij <redacted>
Cc: Alexandre Courbot <redacted>
Cc: linux-gpio at vger.kernel.org
Cc: linux-kernel at vger.kernel.org

This seems like a separate patch from the other 19 patches so please send it
separately so I can handle logistics easier in the future.

Ok, I'll send the next version separately.

quoted

@@ -133,6 +134,7 @@ struct pca953x_chip {
         const char *const *names;
         unsigned long driver_data;
         struct regulator *regulator;
+       struct gpio_desc *reset_gpio;

Why do you even keep this around in the device state container?

As you only use it in the probe() function, use a local variable.

The descriptor will be free():ed by the devm infrastructure anyways.

I think my reasoning for putting the gpio handle into the device
struct was for possibly using it for run-time reset control at some
point. But that could be done later if needed, so I'll go ahead and
make it local.

quoted

+               /* see if we need to de-assert a reset pin */
+               chip->reset_gpio = devm_gpiod_get_optional(&client->dev,
+                                                          "reset",
+                                                          GPIOD_OUT_LOW);
+               if (IS_ERR(chip->reset_gpio)) {
+                       dev_err(&client->dev, "request for reset pin failed\n");
+                       return PTR_ERR(chip->reset_gpio);
+               }

Nice.

quoted

+               if (chip->reset_gpio) {
+                       /* bring chip out of reset */
+                       dev_info(&client->dev, "releasing reset\n");
+                       gpiod_set_value(chip->reset_gpio, 0);
+               }

Is this really needed given that you set it low in the
devm_gpiod_get_optional()?

Yep, this is left over from a previous iteration, but it isn't needed now.
I'll remove it.

Steve