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Message-ID: <255ecc1c-d97a-71ad-62b4-de71fd44292f@linaro.org>
Date: Tue, 30 May 2023 01:17:13 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Marijn Suijten <marijn.suijten@...ainline.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>,
Sam Ravnborg <sam@...nborg.org>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Caleb Connolly <caleb@...nolly.tech>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Andy Gross <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
~postmarketos/upstreaming@...ts.sr.ht,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...ainline.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Martin Botka <martin.botka@...ainline.org>,
Jami Kettunen <jami.kettunen@...ainline.org>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
Abhinav Kumar <quic_abhinavk@...cinc.com>,
Kuogee Hsieh <quic_khsieh@...cinc.com>,
Jessica Zhang <quic_jesszhan@...cinc.com>
Subject: Re: [PATCH RFC 03/10] drm/panel: Add LGD panel driver for Sony Xperia
XZ3
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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