Re: [RFC 08/11] gpiolib: cdev: Add hardware timestamp clock type

On Thu, Jul 29, 2021 at 08:07:15PM -0700, Dipen Patel wrote:

On 7/1/21 7:24 AM, Kent Gibson wrote:

<snip>

quoted

quoted

 			ret = gpiod_direction_output(desc, val);
 			if (ret)
 				return ret;

@@ -1152,6 +1186,13 @@ static long linereq_set_config_unlocked(struct linereq *lr,
 					polarity_change);
 			if (ret)
 				return ret;
+
+			/* Check if new config sets hardware assisted clock */
+			if (flags & GPIO_V2_LINE_FLAG_EVENT_CLOCK_HARDWARE) {
+				ret = gpiod_hw_timestamp_control(desc, true);
+				if (ret)
+					return ret;
+			}
 		}
 

The error code here can come from the pinctrl timestamp_control(), so it
should be sanitised before being returned to userspace.

I do not understand what do you mean by sanitise. I just followed what

gpiod_direction_output did just above which also returns ret from gpio

driver code similar to timestamp_control API.

In this context, sanitise means convert any kernel internal error codes
to their userspace equivalent before returning them to userspace.

Fair enough with the gpiod_direction_output() comparison.  I was thinking
of a patch Andy recently submitted[1] to sanitise gpiod_request(), which
can sometimes return EPROBE_DEFER.  But I guess we can wait until we find
a case of a driver returning an internal error code and add a sanitiser
then.

Cheers,
Kent.

[1] https://www.spinics.net/lists/linux-gpio/msg60998.html