[media] v4l2-ioctl.c: always copy G/S_EDID result

The VIDIOC_G/S_EDID ioctls can return valid data even if an error is returned.

Mark those ioctls accordingly. Rather than using an explicit 'if' to check for the
ioctl (as was done until now for VIDIOC_QUERY_DV_TIMINGS) just set a new flag in the
v4l2_ioctls array.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -2481,6 +2481,8 @@ struct v4l2_ioctl_info {
 #define INFO_FL_FUNC		(1 << 3)
 /* Queuing ioctl */
 #define INFO_FL_QUEUE		(1 << 4)
+/* Always copy back result, even on error */
+#define INFO_FL_ALWAYS_COPY	(1 << 5)
 /* Zero struct from after the field to the end */
 #define INFO_FL_CLEAR(v4l2_struct, field)			\
 	((offsetof(struct v4l2_struct, field) +			\
@@ -2536,8 +2538,8 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
 	IOCTL_INFO_FNC(VIDIOC_QUERYMENU, v4l_querymenu, v4l_print_querymenu, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_querymenu, index)),
 	IOCTL_INFO_STD(VIDIOC_G_INPUT, vidioc_g_input, v4l_print_u32, 0),
 	IOCTL_INFO_FNC(VIDIOC_S_INPUT, v4l_s_input, v4l_print_u32, INFO_FL_PRIO),
-	IOCTL_INFO_STD(VIDIOC_G_EDID, vidioc_g_edid, v4l_print_edid, 0),
-	IOCTL_INFO_STD(VIDIOC_S_EDID, vidioc_s_edid, v4l_print_edid, INFO_FL_PRIO),
+	IOCTL_INFO_STD(VIDIOC_G_EDID, vidioc_g_edid, v4l_print_edid, INFO_FL_ALWAYS_COPY),
+	IOCTL_INFO_STD(VIDIOC_S_EDID, vidioc_s_edid, v4l_print_edid, INFO_FL_PRIO | INFO_FL_ALWAYS_COPY),
 	IOCTL_INFO_STD(VIDIOC_G_OUTPUT, vidioc_g_output, v4l_print_u32, 0),
 	IOCTL_INFO_FNC(VIDIOC_S_OUTPUT, v4l_s_output, v4l_print_u32, INFO_FL_PRIO),
 	IOCTL_INFO_FNC(VIDIOC_ENUMOUTPUT, v4l_enumoutput, v4l_print_enumoutput, INFO_FL_CLEAR(v4l2_output, index)),
@@ -2583,7 +2585,7 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
 	IOCTL_INFO_FNC(VIDIOC_CREATE_BUFS, v4l_create_bufs, v4l_print_create_buffers, INFO_FL_PRIO | INFO_FL_QUEUE),
 	IOCTL_INFO_FNC(VIDIOC_PREPARE_BUF, v4l_prepare_buf, v4l_print_buffer, INFO_FL_QUEUE),
 	IOCTL_INFO_STD(VIDIOC_ENUM_DV_TIMINGS, vidioc_enum_dv_timings, v4l_print_enum_dv_timings, INFO_FL_CLEAR(v4l2_enum_dv_timings, pad)),
-	IOCTL_INFO_STD(VIDIOC_QUERY_DV_TIMINGS, vidioc_query_dv_timings, v4l_print_dv_timings, 0),
+	IOCTL_INFO_STD(VIDIOC_QUERY_DV_TIMINGS, vidioc_query_dv_timings, v4l_print_dv_timings, INFO_FL_ALWAYS_COPY),
 	IOCTL_INFO_STD(VIDIOC_DV_TIMINGS_CAP, vidioc_dv_timings_cap, v4l_print_dv_timings_cap, INFO_FL_CLEAR(v4l2_dv_timings_cap, type)),
 	IOCTL_INFO_FNC(VIDIOC_ENUM_FREQ_BANDS, v4l_enum_freq_bands, v4l_print_freq_band, 0),
 	IOCTL_INFO_FNC(VIDIOC_DBG_G_CHIP_INFO, v4l_dbg_g_chip_info, v4l_print_dbg_chip_info, INFO_FL_CLEAR(v4l2_dbg_chip_info, match)),
@@ -2801,6 +2803,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
 	void	*parg = (void *)arg;
 	long	err  = -EINVAL;
 	bool	has_array_args;
+	bool	always_copy = false;
 	size_t  array_size = 0;
 	void __user *user_ptr = NULL;
 	void	**kernel_ptr = NULL;
@@ -2830,8 +2833,10 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
 			 */
 			if (v4l2_is_known_ioctl(cmd)) {
 				u32 flags = v4l2_ioctls[_IOC_NR(cmd)].flags;
+
 				if (flags & INFO_FL_CLEAR_MASK)
 					n = (flags & INFO_FL_CLEAR_MASK) >> 16;
+				always_copy = flags & INFO_FL_ALWAYS_COPY;
 			}
 
 			if (copy_from_user(parg, (void __user *)arg, n))
@@ -2885,9 +2890,11 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
 			err = -EFAULT;
 		goto out_array_args;
 	}
-	/* VIDIOC_QUERY_DV_TIMINGS can return an error, but still have valid
-	   results that must be returned. */
-	if (err < 0 && cmd != VIDIOC_QUERY_DV_TIMINGS)
+	/*
+	 * Some ioctls can return an error, but still have valid
+	 * results that must be returned.
+	 */
+	if (err < 0 && !always_copy)
 		goto out;
 
 out_array_args: