diff mbox series

[RFC,2/3] media: i2c: adv7842: remove open coded version of SMBus block read

Message ID 20210112164130.47895-3-wsa+renesas@sang-engineering.com
State New
Headers show
Series treewide: remove open coded SMBus block transfers | expand

Commit Message

Wolfram Sang Jan. 12, 2021, 4:41 p.m. UTC 
The open coded version differs from the one in the core in one way: the
buffer will be always copied back, even when the transfer failed. It
looks like it is expected that the sanity check for a correct CRC and
header will bail out later.

Use the block read from the I2C core and propagate a potential errno
further to the sanity check.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Note: we could now make the error checking even stronger by checking if
the number of received bytes is I2C_SMBUS_BLOCK_MAX. But to avoid
regressions, I kept the logic as is, i.e. only check for errno.

 drivers/media/i2c/adv7511-v4l2.c | 40 +++++++++++---------------------
 1 file changed, 14 insertions(+), 26 deletions(-)

Comments

Wolfram Sang Jan. 12, 2021, 7:41 p.m. UTC | #1 
> +static int adv7511_edid_rd(struct v4l2_subdev *sd, uint16_t len, uint8_t *buf)
>  {
>  	struct adv7511_state *state = get_adv7511_state(sd);
> +	s32 len;

And 'len' here shadows the function argument :( Ok, I need to resend
this patch. Still, looking forward to a comment if an approach like this
is acceptable.
Wolfram Sang Jan. 18, 2021, 9:33 a.m. UTC | #2 
Hello Hans,

I hope you are well!

> > The open coded version differs from the one in the core in one way: the
> > buffer will be always copied back, even when the transfer failed. It
> > looks like it is expected that the sanity check for a correct CRC and
> > header will bail out later.
> 
> Nah, it's just a bug. It should have returned and checked the error code,
> so your patch does the right thing.

I see. So, I will only update the commit message.

Thanks for the reviews!

All the best,

   Wolfram
diff mbox series

Patch

diff --git a/drivers/media/i2c/adv7511-v4l2.c b/drivers/media/i2c/adv7511-v4l2.c
index a3161d709015..0150f76dc6a6 100644
--- a/drivers/media/i2c/adv7511-v4l2.c
+++ b/drivers/media/i2c/adv7511-v4l2.c
@@ -214,36 +214,24 @@  static inline void adv7511_wr_and_or(struct v4l2_subdev *sd, u8 reg, u8 clr_mask
 	adv7511_wr(sd, reg, (adv7511_rd(sd, reg) & clr_mask) | val_mask);
 }
 
-static int adv_smbus_read_i2c_block_data(struct i2c_client *client,
-					 u8 command, unsigned length, u8 *values)
-{
-	union i2c_smbus_data data;
-	int ret;
-
-	if (length > I2C_SMBUS_BLOCK_MAX)
-		length = I2C_SMBUS_BLOCK_MAX;
-	data.block[0] = length;
-
-	ret = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
-			     I2C_SMBUS_READ, command,
-			     I2C_SMBUS_I2C_BLOCK_DATA, &data);
-	memcpy(values, data.block + 1, length);
-	return ret;
-}
-
-static void adv7511_edid_rd(struct v4l2_subdev *sd, uint16_t len, uint8_t *buf)
+static int adv7511_edid_rd(struct v4l2_subdev *sd, uint16_t len, uint8_t *buf)
 {
 	struct adv7511_state *state = get_adv7511_state(sd);
+	s32 len;
 	int i;
-	int err = 0;
 
 	v4l2_dbg(1, debug, sd, "%s:\n", __func__);
 
-	for (i = 0; !err && i < len; i += I2C_SMBUS_BLOCK_MAX)
-		err = adv_smbus_read_i2c_block_data(state->i2c_edid, i,
+	for (i = 0; i < len; i += I2C_SMBUS_BLOCK_MAX) {
+		len = i2c_smbus_read_i2c_block_data(state->i2c_edid, i,
 						    I2C_SMBUS_BLOCK_MAX, buf + i);
-	if (err)
-		v4l2_err(sd, "%s: i2c read error\n", __func__);
+		if (len < 0) {
+			v4l2_err(sd, "%s: i2c read error\n", __func__);
+			return len;
+		}
+	}
+
+	return 0;
 }
 
 static inline int adv7511_cec_read(struct v4l2_subdev *sd, u8 reg)
@@ -1668,20 +1656,20 @@  static bool adv7511_check_edid_status(struct v4l2_subdev *sd)
 	if (edidRdy & MASK_ADV7511_EDID_RDY) {
 		int segment = adv7511_rd(sd, 0xc4);
 		struct adv7511_edid_detect ed;
+		int err;
 
 		if (segment >= EDID_MAX_SEGM) {
 			v4l2_err(sd, "edid segment number too big\n");
 			return false;
 		}
 		v4l2_dbg(1, debug, sd, "%s: got segment %d\n", __func__, segment);
-		adv7511_edid_rd(sd, 256, &state->edid.data[segment * 256]);
+		err = adv7511_edid_rd(sd, 256, &state->edid.data[segment * 256]);
 		adv7511_dbg_dump_edid(2, debug, sd, segment, &state->edid.data[segment * 256]);
 		if (segment == 0) {
 			state->edid.blocks = state->edid.data[0x7e] + 1;
 			v4l2_dbg(1, debug, sd, "%s: %d blocks in total\n", __func__, state->edid.blocks);
 		}
-		if (!edid_verify_crc(sd, segment) ||
-		    !edid_verify_header(sd, segment)) {
+		if (err < 0 || !edid_verify_crc(sd, segment) || !edid_verify_header(sd, segment)) {
 			/* edid crc error, force reread of edid segment */
 			v4l2_err(sd, "%s: edid crc or header error\n", __func__);
 			state->have_monitor = false;