Hi Dmitry,

Thank you for reviewing the patches.

On 31/05/24 04:51, Dmitry Baryshkov wrote:
> On Thu, May 30, 2024 at 03:06:19PM +0530, Aradhya Bhatia wrote:
>> Change the existing (and deprecated) bridge hooks, to the bridge
>> atomic APIs.
>>
>> Add drm helpers for duplicate_state, destroy_state, and bridge_reset
>> bridge hooks.
>>
>> Further add support for the input format negotiation hook.
>>
>> Signed-off-by: Aradhya Bhatia <a-bhat...@ti.com>
>> ---
>>  .../gpu/drm/bridge/cadence/cdns-dsi-core.c    | 70 ++++++++++++++++---
>>  1 file changed, 62 insertions(+), 8 deletions(-)
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
> 
> Minor nit below.
> 
>>
>> @@ -915,13 +920,62 @@ static void cdns_dsi_bridge_pre_enable(struct 
>> drm_bridge *bridge)
>>      cdns_dsi_hs_init(dsi);
>>  }
>>  
>> +static u32 *cdns_dsi_bridge_get_input_bus_fmts(struct drm_bridge *bridge,
>> +                                           struct drm_bridge_state 
>> *bridge_state,
>> +                                           struct drm_crtc_state 
>> *crtc_state,
>> +                                           struct drm_connector_state 
>> *conn_state,
>> +                                           u32 output_fmt,
>> +                                           unsigned int *num_input_fmts)
>> +{
> 
> This code below looks pretty generic. Would be logical to extract it to
> a helper and allow it to be used by other DSI host bridges?

I agree, it would indeed make sense.

I just tried to make a helper function that could directly be passed to
the drm_bridge_funcs list - like we do with
"drm_atomic_helper_bridge_propagate_bus_fmt". This would have been ideal
in my opinion.

But, that doesn't seem possible today. The parameter "output_fmt"
doesn't describe any of the DSI pixel formats from "enum
mipi_dsi_pixel_format", which is what's required to ascertain the input
bus format for dsi hosts. Neither do the drm_bridge{_state} help with
that.

For now, I am thinking to just add a common function that accepts the
dsi bus output format and returns the corresponding input bus format.
With this, every dsi host will still need to implement their own
get_input_fmt hook and call that function.

If you had something else in mind, do let me know! =)

Regards
Aradhya

> 
>> +    struct cdns_dsi_input *input = bridge_to_cdns_dsi_input(bridge);
>> +    struct cdns_dsi *dsi = input_to_dsi(input);
>> +    struct cdns_dsi_output *output = &dsi->output;
>> +    u32 *input_fmts;
>> +
>> +    *num_input_fmts = 0;
>> +
>> +    input_fmts = kzalloc(sizeof(*input_fmts), GFP_KERNEL);
>> +    if (!input_fmts)
>> +            return NULL;
>> +
>> +    switch (output->dev->format) {
>> +    case MIPI_DSI_FMT_RGB888:
>> +            input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
>> +            break;
>> +
>> +    case MIPI_DSI_FMT_RGB666:
>> +            input_fmts[0] = MEDIA_BUS_FMT_RGB666_1X24_CPADHI;
>> +            break;
>> +
>> +    case MIPI_DSI_FMT_RGB666_PACKED:
>> +            input_fmts[0] = MEDIA_BUS_FMT_RGB666_1X18;
>> +            break;
>> +
>> +    case MIPI_DSI_FMT_RGB565:
>> +            input_fmts[0] = MEDIA_BUS_FMT_RGB565_1X16;
>> +            break;
>> +
>> +    default:
>> +            /* Unsupported DSI Format */
>> +            return NULL;
>> +    }
>> +
>> +    *num_input_fmts = 1;
>> +
>> +    return input_fmts;
>> +}
>> +
> 

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