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SubjectRe: [PATCH RFC 03/10] drm/panel: Add LGD panel driver for Sony Xperia XZ3
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On 30/05/2023 00:11, 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.
>
>>> + drm_dsc_pps_payload_pack(&pps, ctx->dsi->dsc);
>>> +
>>> + ret = mipi_dsi_picture_parameter_set(ctx->dsi, &pps);
>>> + if (ret < 0) {
>>> + dev_err(panel->dev, "failed to transmit PPS: %d\n", ret);
>>> + goto fail;
>>> + }
>>> + ret = mipi_dsi_compression_mode(ctx->dsi, true);
>>> + if (ret < 0) {
>>> + dev_err(dev, "failed to enable compression mode: %d\n", ret);
>>> + goto fail;
>>> + }
>>> +
>>> + msleep(28);
>>> + }
>>> +
>>> + ctx->prepared = true;
>>> + return 0;
>>> +
>>> +fail:
>>> + gpiod_set_value_cansleep(ctx->reset_gpio, 0);
>>> + regulator_disable(ctx->vddio);
>>> + return ret;
>>> +}
> <snip>
>>> + /* This panel only supports DSC; unconditionally enable it */
>
> On that note I should perhaps reword this.
>
>>> + dsi->dsc = dsc = devm_kzalloc(&dsi->dev, sizeof(*dsc), GFP_KERNEL);
>>
>> I think double assignments are frowned upon.
>
> Ack.
>
>>
>>> + if (!dsc)
>>> + return -ENOMEM;
>>> +
>>> + dsc->dsc_version_major = 1;
>>> + dsc->dsc_version_minor = 1;
>>> +
>>> + dsc->slice_height = 32;
>>> + dsc->slice_count = 2;
>>> + // TODO: Get hdisplay from the mode
>>
>> Would you like to fix the TODO?
>
> I can't unless either migrating to drm_bridge (is that doable?) or
> expand drm_panel. That's a larger task, but I don't think this driver
> is the right place to track that desire. Should I drop the comment
> entirely or reword it?

I'd say, reword it, so that it becomes more obvious why this TODO can
not be fixed at this moment.

>
>>> + WARN_ON(1440 % dsc->slice_count);
>>> + dsc->slice_width = 1440 / dsc->slice_count;
>
> <snip>
>
> - Marijn

--
With best wishes
Dmitry

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