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From:   Guillaume Ranquet <granquet@baylibre.com>
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Date:   Wed, 15 Dec 2021 07:59:35 -0600
Message-ID: <CABnWg9tAMLWtPK1QjiqKyNgNhdqDDSc2fyAAmS3rzLQBwvT8SA@mail.gmail.com>
Subject: Re: [PATCH v6 7/7] drm/mediatek: Add mt8195 DisplayPort driver
To:     Hsin-Yi Wang <hsinyi@chromium.org>
Cc:     Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Markus Schneider-Pargmann <msp@baylibre.com>,
        kernel test robot <lkp@intel.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-mediatek@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org
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Hi Hsin-Yi,

Quoting Hsin-Yi Wang (2021-12-09 07:29:30)
> On Wed, Nov 10, 2021 at 9:08 PM Guillaume Ranquet <granquet@baylibre.com> wrote:
> >
> > From: Markus Schneider-Pargmann <msp@baylibre.com>
> >
> > This patch adds a DisplayPort driver for the Mediatek mt8195 SoC and a
> > according phy driver mediatek-dp-phy.
> >
> > It supports both functional units on the mt8195, the embedded
> > DisplayPort as well as the external DisplayPort units. It offers
> > hot-plug-detection, audio up to 8 channels, and DisplayPort 1.4 with up
> > to 4 lanes.
> >
> > The driver creates a child device for the phy. The child device will
> > never exist without the parent being active. As they are sharing a
> > register range, the parent passes a regmap pointer to the child so that
> > both can work with the same register range. The phy driver sets device
> > data that is read by the parent to get the phy device that can be used
> > to control the phy properties.
> >
> > This driver is based on an initial version by
> > Jason-JH.Lin <jason-jh.lin@mediatek.com>.
> >
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > Reported-by: kernel test robot <lkp@intel.com>
> > ---
>
>
> <snip>
>
> > +static int mtk_dp_probe(struct platform_device *pdev)
> > +{
> > +       struct mtk_dp *mtk_dp;
> > +       struct device *dev = &pdev->dev;
> > +       int ret;
> > +       int irq_num = 0;
> > +       struct drm_panel *panel = NULL;
> > +
> > +       mtk_dp = devm_kzalloc(dev, sizeof(*mtk_dp), GFP_KERNEL);
> > +       if (!mtk_dp)
> > +               return -ENOMEM;
> > +
> > +       mtk_dp->dev = dev;
> > +
> > +       irq_num = platform_get_irq(pdev, 0);
> > +       if (irq_num < 0) {
> > +               dev_err(dev, "failed to request dp irq resource\n");
> > +               return -EPROBE_DEFER;
> > +       }
> > +
> > +       ret = drm_of_find_panel_or_bridge(dev->of_node, 1, 0, &panel,
> > +                                         &mtk_dp->next_bridge);
> > +       if (ret == -ENODEV) {
> > +               dev_info(
> > +                       dev,
> > +                       "No panel connected in devicetree, continuing as external DP\n");
> > +               mtk_dp->next_bridge = NULL;
> > +       } else if (ret) {
> > +               dev_err(dev, "Failed to find panel or bridge: %d\n", ret);
>
> Hi,
>
> We're seeing
> [    0.424599] mediatek-drm-dp 1c500000.edp_tx: Failed to find panel
> or bridge: -517
>
> It's probably better to use dev_err_probe here.
>
> Thanks

Good suggestion, it will be in v7.

Thanks for your review,
Guillaume.
>
> > +               return ret;
> > +       }
> > +
> > +       if (panel) {
> > +               mtk_dp->next_bridge = devm_drm_panel_bridge_add(dev, panel);
> > +               if (IS_ERR(mtk_dp->next_bridge)) {
> > +                       ret = PTR_ERR(mtk_dp->next_bridge);
> > +                       dev_err(dev, "Failed to create bridge: %d\n", ret);
> > +                       return -EPROBE_DEFER;
> > +               }
> > +       }
>
>
> <snip>
>
> > _______________________________________________
> > Linux-mediatek mailing list
> > Linux-mediatek@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-mediatek