[RFC,2/3] media: i2c: adv7842: remove open coded version of SMBus block read
Commit Message
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
On Tue, Jan 12, 2021 at 05:41:28PM +0100, Wolfram Sang wrote:
> 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>
$subject should say "adv7511", sorry!
> +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.
Hi Wolfram,
On 12/01/2021 17:41, Wolfram Sang wrote:
> 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.
Regards,
Hans
>
> 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(-)
>
> 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;
>
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
@@ -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;