Hi Chris,
On Wed, Mar 15, 2017 at 04:42:31PM +0800, Chris Zhong wrote:
> For RK3399, the grf clk should be enabled before writing grf registers,
> otherwise the register value can not be changed.
>
> Signed-off-by: Chris Zhong <zyw@xxxxxxxxxxxxxx>
> ---
>
> drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> index f84f9ae..d8f24f2 100644
> --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
> @@ -291,6 +291,7 @@ struct dw_mipi_dsi {
> struct regmap *grf_regmap;
> void __iomem *base;
>
> + struct clk *grf_clk;
> struct clk *pllref_clk;
> struct clk *pclk;
> struct clk *phy_cfg_clk;
> @@ -979,6 +980,16 @@ static void dw_mipi_dsi_encoder_enable(struct drm_encoder *encoder)
> dw_mipi_dsi_dphy_interface_config(dsi);
> dw_mipi_dsi_clear_err(dsi);
>
> + /*
> + * For the RK3399, the clk of grf must be enabled before writing grf
> + * register.
> + */
> + ret = clk_prepare_enable(dsi->grf_clk);
> + if (ret) {
> + dev_err(dsi->dev, "Failed to enable grf_clk\n");
> + return;
> + }
> +
> if (pdata->grf_dsi0_mode_reg)
> regmap_write(dsi->grf_regmap, pdata->grf_dsi0_mode_reg,
> pdata->grf_dsi0_mode);
> @@ -1003,6 +1014,8 @@ static void dw_mipi_dsi_encoder_enable(struct drm_encoder *encoder)
> regmap_write(dsi->grf_regmap, pdata->grf_switch_reg, val);
> dev_dbg(dsi->dev, "vop %s output to dsi0\n", (mux) ? "LIT" : "BIG");
> dsi->dpms_mode = DRM_MODE_DPMS_ON;
> +
> + clk_disable_unprepare(dsi->grf_clk);
> }
>
> static int
> @@ -1238,6 +1251,17 @@ static int dw_mipi_dsi_bind(struct device *dev, struct device *master,
> dev_dbg(dev, "have not phy_cfg_clk\n");
> }
>
> + dsi->grf_clk = devm_clk_get(dev, "grf");
> + if (IS_ERR(dsi->grf_clk)) {
> + ret = PTR_ERR(dsi->grf_clk);
> + if (ret != -ENOENT) {
> + dev_err(dev, "Unable to get grf_clk: %d\n", ret);
If you're going to print an error, you should probably check for
-EPROBE_DEFER. This driver isn't quite consistent about this.
> + return ret;
> + }
> + dsi->grf_clk = NULL;
> + dev_dbg(dev, "have not grf_clk\n");
The wording is a little awkward; maybe "no grf_clk provided\n"?
Also, to be clear, this clock is required for RK3399, but not for others
(e.g., RK3288) right? I guess this makes sense then, to just treat it as
optional for all cases, even if you document it as "required" for
RK3399.
Brian
> + }
> +
> ret = clk_prepare_enable(dsi->pllref_clk);
> if (ret) {
> dev_err(dev, "%s: Failed to enable pllref_clk\n", __func__);
Brian
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