linux-kernel - Re: [PATCH v3 1/4] drm/rockchip: dsi: Hold pm-runtime across bind/unbind

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Date:   Wed, 29 Sep 2021 10:27:46 +0800
From:   Chen-Yu Tsai <wenst@...omium.org>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Heiko Stübner <heiko@...ech.de>,
        LKML <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Sandy Huang <hjc@...k-chips.com>,
        Thomas Hebb <tommyhebb@...il.com>,
        aleksandr.o.makarov@...il.com, stable@...r.kernel.org,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>
Subject: Re: [PATCH v3 1/4] drm/rockchip: dsi: Hold pm-runtime across bind/unbind

On Wed, Sep 29, 2021 at 5:36 AM Brian Norris <briannorris@...omium.org> wrote:
>
> In commit 43c2de1002d2, we moved most HW configuration to bind(), but we
> didn't move the runtime PM management. Therefore, depending on initial
> boot state, runtime-PM workqueue delays, and other timing factors, we
> may disable our power domain in between the hardware configuration
> (bind()) and when we enable the display. This can cause us to lose
> hardware state and fail to configure our display. For example:
>
>   dw-mipi-dsi-rockchip ff968000.mipi: failed to write command FIFO
>   panel-innolux-p079zca ff960000.mipi.0: failed to write command 0
>
> or:
>
>   dw-mipi-dsi-rockchip ff968000.mipi: failed to write command FIFO
>   panel-kingdisplay-kd097d04 ff960000.mipi.0: failed write init cmds: -110
>
> We should match the runtime PM to the lifetime of the bind()/unbind()
> cycle.
>
> Tested on Acer Chrometab 10 (RK3399 Gru-Scarlet), with panel drivers
> built either as modules or built-in.
>
> Side notes: it seems one is more likely to see this problem when the
> panel driver is built into the kernel. I've also seen this problem
> bisect down to commits that simply changed Kconfig dependencies, because
> it changed the order in which driver init functions were compiled into
> the kernel, and therefore the ordering and timing of built-in device
> probe.
>
> Fixes: 43c2de1002d2 ("drm/rockchip: dsi: move all lane config except LCDC mux to bind()")
> Link: https://lore.kernel.org/linux-rockchip/9aedfb528600ecf871885f7293ca4207c84d16c1.camel@gmail.com/
> Reported-by: <aleksandr.o.makarov@...il.com>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Brian Norris <briannorris@...omium.org>
> Tested-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>