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

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Message-ID: <13120578.oI4PYoXzsg@phil>
Date:   Sun, 17 Oct 2021 23:55:42 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Brian Norris <briannorris@...omium.org>
Cc:     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>,
        Brian Norris <briannorris@...omium.org>, stable@...r.kernel.org
Subject: Re: [PATCH v3 2/4] drm/rockchip: dsi: Reconfigure hardware on resume()

Am Dienstag, 28. September 2021, 23:35:50 CEST schrieb Brian Norris:
> 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),

not always though. In non-atomic settings .mode_set actually doesn't
seem to be called every time. I've experienced this when drm disables
atomic when X11 is running.

So having real suspend/resume callbacks makes quite a lot of sense :-)


Heiko

> 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>
> ---
> 
> Changes in v3:
>  - New patch, to fix related PM issue discovered after patch 1
> 
>  .../gpu/drm/rockchip/dw-mipi-dsi-rockchip.c   | 37 +++++++++++++++++++
>  1 file changed, 37 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> index 45676b23c019..21c67343cc6c 100644
> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
> @@ -268,6 +268,8 @@ struct dw_mipi_dsi_rockchip {
>  	struct dw_mipi_dsi *dmd;
>  	const struct rockchip_dw_dsi_chip_data *cdata;
>  	struct dw_mipi_dsi_plat_data pdata;
> +
> +	bool dsi_bound;
>  };
>  
>  struct dphy_pll_parameter_map {
> @@ -964,6 +966,8 @@ static int dw_mipi_dsi_rockchip_bind(struct device *dev,
>  		goto out_pm_runtime;
>  	}
>  
> +	dsi->dsi_bound = true;
> +
>  	return 0;
>  
>  out_pm_runtime:
> @@ -983,6 +987,8 @@ static void dw_mipi_dsi_rockchip_unbind(struct device *dev,
>  	if (dsi->is_slave)
>  		return;
>  
> +	dsi->dsi_bound = false;
> +
>  	dw_mipi_dsi_unbind(dsi->dmd);
>  
>  	clk_disable_unprepare(dsi->pllref_clk);
> @@ -1277,6 +1283,36 @@ static const struct phy_ops dw_mipi_dsi_dphy_ops = {
>  	.exit		= dw_mipi_dsi_dphy_exit,
>  };
>  
> +static int __maybe_unused dw_mipi_dsi_rockchip_resume(struct device *dev)
> +{
> +	struct dw_mipi_dsi_rockchip *dsi = dev_get_drvdata(dev);
> +	int ret;
> +
> +	/*
> +	 * Re-configure DSI state, if we were previously initialized. We need
> +	 * to do this before rockchip_drm_drv tries to re-enable() any panels.
> +	 */
> +	if (dsi->dsi_bound) {
> +		ret = clk_prepare_enable(dsi->grf_clk);
> +		if (ret) {
> +			DRM_DEV_ERROR(dsi->dev, "Failed to enable grf_clk: %d\n", ret);
> +			return ret;
> +		}
> +
> +		dw_mipi_dsi_rockchip_config(dsi);
> +		if (dsi->slave)
> +			dw_mipi_dsi_rockchip_config(dsi->slave);
> +
> +		clk_disable_unprepare(dsi->grf_clk);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops dw_mipi_dsi_rockchip_pm_ops = {
> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(NULL, dw_mipi_dsi_rockchip_resume)
> +};
> +
>  static int dw_mipi_dsi_rockchip_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -1594,6 +1630,7 @@ struct platform_driver dw_mipi_dsi_rockchip_driver = {
>  	.remove		= dw_mipi_dsi_rockchip_remove,
>  	.driver		= {
>  		.of_match_table = dw_mipi_dsi_rockchip_dt_ids,
> +		.pm	= &dw_mipi_dsi_rockchip_pm_ops,
>  		.name	= "dw-mipi-dsi-rockchip",
>  	},
>  };
>