On Tue, 30 May 2023 at 10:24, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
>
> Hi Marijn, Dmitry, Caleb, Jessica,
>
> On 29/05/2023 23:11, Marijn Suijten wrote:
> > On 2023-05-22 04:16:20, Dmitry Baryshkov wrote:
> > <snip>
> >>> + if (ctx->dsi->dsc) {
> >>
> >> dsi->dsc is always set, thus this condition can be dropped.
> >
> > I want to leave room for possibly running the panel without DSC (at a
> > lower resolution/refresh rate, or at higher power consumption if there
> > is enough BW) by not assigning the pointer, if we get access to panel
> > documentation: probably one of the magic commands sent in this driver
> > controls it but we don't know which.
>
> I'd like to investigate if DSC should perhaps only be enabled if we
> run non certain platforms/socs ?
>
> I mean, we don't know if the controller supports DSC and those particular
> DSC parameters so we should probably start adding something like :
>
> static drm_dsc_config dsc_params_qcom = {}
>
> static const struct of_device_id panel_of_dsc_params[] = {
> { .compatible = "qcom,sm8150", , .data = &dsc_params_qcom },
> { .compatible = "qcom,sm8250", , .data = &dsc_params_qcom },
> { .compatible = "qcom,sm8350", , .data = &dsc_params_qcom },
> { .compatible = "qcom,sm8450", , .data = &dsc_params_qcom },
> };
I think this would damage the reusability of the drivers. The panel
driver does not actually care if the SoC is SM8350, sunxi-something or
RCar.
Instead it cares about host capabilities.
I think instead we should extend mipi_dsi_host:
#define MIPI_DSI_HOST_MODE_VIDEO BIT(0)
#define MIPI_DSI_HOST_MODE_CMD BIT(1)
#define MIPI_DSI_HOST_VIDEO_SUPPORTS_COMMANDS BIT(2)
// FIXME: do we need to provide additional caps here ?
#define MIPI_DSI_DSC_1_1 BIT(0)
#define MIPI_DSI_DSC_1_2 BIT(1)
#define MIPI_DSI_DSC_NATIVE_422 BIT(2)
#define MIPI_DSI_DSC_NATIVE_420 BIT(3)
#define MIPI_DSI_DSC_FRAC_BPP BIT(4)
// etc.
struct mipi_dsi_host {
// new fields only
unsigned long mode_flags;
unsigned long dsc_flags;
};
Then the panel driver can adapt itself to the host capabilities and
(possibly) select one of the internally supported DSC profiles.
>
> ...
> static int sony_akatsuki_lgd_probe(struct mipi_dsi_device *dsi)
> ...
> const struct of_device_id *match;
>
> ...
> match = of_match_node(panel_of_dsc_params, of_root);
> if (match && match->data) {
> dsi->dsc = devm_kzalloc(&dsi->dev, sizeof(*dsc), GFP_KERNEL);
> memcpy(dsi->dsc, match->data, sizeof(*dsc));
> } else {
> dev_warn(&dsi->dev, "DSI controller is not marked as supporting DSC\n");
> }
> ...
> }
>
> and probably bail out if it's a DSC only panel.
>
> We could alternatively match on the DSI controller's dsi->host->dev instead of the SoC root compatible.
>
> Neil
--
With best wishes
Dmitry
