On Wed, Jun 05, 2019 at 04:18:49PM +0200, Michal Simek wrote:
> On 04. 06. 19 23:55, Robert Hancock wrote:
> > This driver does not support reading more than 255 bytes at once because
> > the register for storing the number of bytes to read is only 8 bits. Add
> > a max_read_len quirk to enforce this.
> >
> > This was found when using this driver with the SFP driver, which was
> > previously reading all 256 bytes in the SFP EEPROM in one transaction.
> > This caused a bunch of hard-to-debug errors in the xiic driver since the
> > driver/logic was treating the number of bytes to read as zero.
> > Rejecting transactions that aren't supported at least allows the problem
> > to be diagnosed more easily.
> >
> > Signed-off-by: Robert Hancock <hancock@xxxxxxxxxxxxx>
Thanks for the patch!
> > ---
> >
> > Changes since v1: Added more rationale in description.
> >
> > drivers/i2c/busses/i2c-xiic.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
> > index 0fea7c5..37b3b93 100644
> > --- a/drivers/i2c/busses/i2c-xiic.c
> > +++ b/drivers/i2c/busses/i2c-xiic.c
> > @@ -709,11 +709,16 @@ static u32 xiic_func(struct i2c_adapter *adap)
> > .functionality = xiic_func,
> > };
> >
> > +static const struct i2c_adapter_quirks xiic_quirks = {
> > + .max_read_len = 255,
> > +};
> > +
> > static const struct i2c_adapter xiic_adapter = {
> > .owner = THIS_MODULE,
> > .name = DRIVER_NAME,
> > .class = I2C_CLASS_DEPRECATED,
> > .algo = &xiic_algorithm,
> > + .quirks = &xiic_quirks,
> > };
> >
>
> Reviewed-by: Michal Simek <michal.simek@xxxxxxxxxx>
>
> Nit: The same limitation is there for write. Maybe worth to also set it
> up. Anyway this can be done separately.
I consider this stable material, so I'd prefer to have both fixed in one
patch, if possible.
Robert, are you willing to add this?
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