[PATCH v3] drm/bridge/sii902x: Fix EDID readback

[Peter Rosin]

On 2018-11-06 12:52, Fabrizio Castro wrote:
> While adding SiI9022A support to the iwg23s board, it came
> up that when the HDMI transmitter is in pass through mode the
> device is not compliant with the I2C specification anymore,
> as it requires a far bigger tbuf, due to a delay the HDMI
> transmitter is adding when relaying the STOP condition on the
> monitor i2c side of things.
> 
> When not providing an appropriate delay after the STOP condition
> the i2c bus would get stuck. Also, any other traffic on the bus
> while talking to the monitor may cause the transaction to fail
> or even cause issues with the i2c bus as well.
> 
> I2c-gates seemed to reach consent as a possible way to address
> these issues, and as such this patch is implementing a solution
> based on that. Since others are clearly relying on the current
> implementation of the driver, this patch won't require any DT
> changes.
> 
> Since we don't want any interference during the DDC Bus
> Request/Grant procedure and while talking to the monitor, we
> have to use the adapter locking primitives rather than the
> i2c-mux locking primitives.
> 
> Signed-off-by: Fabrizio Castro <fabrizio.castro at bp.renesas.com>

Reviewed-by: Peter Rosin <peda at axentia.se>

Cheers,
Peter

> 
> ---
> v2->v3:
> * Incorporated comments from Boris Brezillon and Peter Rosin
> 
> v1->v2:
> * Incorporated comments from Peter Rosin
> 
>  drivers/gpu/drm/bridge/sii902x.c | 247 ++++++++++++++++++++++++++++-----------
>  1 file changed, 178 insertions(+), 69 deletions(-)