linux-kernel - Re: [PATCH v3 2/4] drm/rockchip: dsi: Reconfigure hardware on resume()

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Message-ID: <20210929180522.3zksg7mpwdut7tra@notapiano>
Date:   Wed, 29 Sep 2021 15:05:22 -0300
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Heiko Stübner <heiko@...ech.de>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-rockchip@...ts.infradead.org,
        Sandy Huang <hjc@...k-chips.com>,
        Chen-Yu Tsai <wenst@...omium.org>,
        Thomas Hebb <tommyhebb@...il.com>, stable@...r.kernel.org
Subject: Re: [PATCH v3 2/4] drm/rockchip: dsi: Reconfigure hardware on
 resume()

On Tue, Sep 28, 2021 at 02:35:50PM -0700, Brian Norris wrote:
> Since commit 43c2de1002d2, we perform most HW configuration in the
> bind() function. This configuration may be lost on suspend/resume, so we
> need to call it again. That may lead to errors like this after system
> suspend/resume:
> 
>   dw-mipi-dsi-rockchip ff968000.mipi: failed to write command FIFO
>   panel-kingdisplay-kd097d04 ff960000.mipi.0: failed write init cmds: -110
> 
> Tested on Acer Chromebook Tab 10 (RK3399 Gru-Scarlet).
> 
> Note that early mailing list versions of this driver borrowed Rockchip's
> downstream/BSP solution, to do HW configuration in mode_set() (which
> *is* called at the appropriate pre-enable() times), but that was
> discarded along the way. I've avoided that still, because mode_set()
> documentation doesn't suggest this kind of purpose as far as I can tell.
> 
> Fixes: 43c2de1002d2 ("drm/rockchip: dsi: move all lane config except LCDC mux to bind()")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Brian Norris <briannorris@...omium.org>

Tested-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>