Hi Laurent,
On Thu, Nov 02, 2023 at 03:22:17AM +0200, Laurent Pinchart wrote:
> Hi Alexander,
>
> Thank you for the patch.
>
> On Wed, Nov 01, 2023 at 01:23:53PM +0100, Alexander Stein wrote:
> > Some sensors, e.g. Sony, are using little-endian registers. Add support for
>
> I would write Sony IMX290 here, as there are Sony sensors that use big
> endian.
Almost all of them. There are a few exceptions indeed. This seems to be a
bug.
>
> > those by encoding the endianess into Bit 20 of the register address.
> >
> > Fixes: af73323b97702 ("media: imx290: Convert to new CCI register access helpers")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-cci.c | 44 ++++++++++++++++++++++++------
> > include/media/v4l2-cci.h | 5 ++++
> > 2 files changed, 41 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-cci.c b/drivers/media/v4l2-core/v4l2-cci.c
> > index bc2dbec019b04..673637b67bf67 100644
> > --- a/drivers/media/v4l2-core/v4l2-cci.c
> > +++ b/drivers/media/v4l2-core/v4l2-cci.c
> > @@ -18,6 +18,7 @@
> >
> > int cci_read(struct regmap *map, u32 reg, u64 *val, int *err)
> > {
> > + bool little_endian;
> > unsigned int len;
> > u8 buf[8];
> > int ret;
> > @@ -25,6 +26,7 @@ int cci_read(struct regmap *map, u32 reg, u64 *val, int *err)
> > if (err && *err)
> > return *err;
> >
> > + little_endian = reg & CCI_REG_LE;
>
> You could initialize the variable when declaring it. Same below.
I was thinking of the same, but then it'd be logical to move initialisation
of all related variables there. reg is modified here though. I'd keep
setting little_endian here. If someone wants to move it, that could be done
in a separate patch.
>
> > len = FIELD_GET(CCI_REG_WIDTH_MASK, reg);
> > reg = FIELD_GET(CCI_REG_ADDR_MASK, reg);
> >
> > @@ -40,16 +42,28 @@ int cci_read(struct regmap *map, u32 reg, u64 *val, int *err)
> > *val = buf[0];
> > break;
> > case 2:
> > - *val = get_unaligned_be16(buf);
> > + if (little_endian)
> > + *val = get_unaligned_le16(buf);
> > + else
> > + *val = get_unaligned_be16(buf);
>
> Unrelated to this patch, isn't buf aligned to a 4 bytes boundary ?
Very probably, as it's right after len that's an unsigned int. Adding
__aligned(8) would ensure we don't need any of the unaligned variants, and
most likely would keep the stack layout as-is.
Or... how about putting it in an union with a u64? That would mean it's
accessible as u64 alignment-wise while the alignment itself is up to the
ABI. A comment would be good to have probably.
>
> > break;
> > case 3:
> > - *val = get_unaligned_be24(buf);
> > + if (little_endian)
> > + *val = get_unaligned_le24(buf);
> > + else
> > + *val = get_unaligned_be24(buf);
> > break;
> > case 4:
> > - *val = get_unaligned_be32(buf);
> > + if (little_endian)
> > + *val = get_unaligned_le32(buf);
> > + else
> > + *val = get_unaligned_be32(buf);
> > break;
> > case 8:
> > - *val = get_unaligned_be64(buf);
> > + if (little_endian)
> > + *val = get_unaligned_le64(buf);
> > + else
> > + *val = get_unaligned_be64(buf);
> > break;
> > default:
> > dev_err(regmap_get_device(map), "Error invalid reg-width %u for reg 0x%04x\n",
--
Regards,
Sakari Ailus
