Re: [PATCH v3 7/9] drm/bridge: ti-sn65dsi86: Group DP link training bits in a function

Bjorn Andersson
2020-02-03T23:39:06Z

On Wed 18 Dec 14:35 PST 2019, Douglas Anderson wrote:

> We'll re-organize the ti_sn_bridge_enable() function a bit to group
> together all the parts relating to link training and split them into a
> sub-function. This is not intended to have any functional change and
> is in preparation for trying link training several times at different
> rates. One small side effect here is that if link training fails
> we'll now leave the DP PLL disabled, but that seems like a sane thing
> to do.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Tested-by: Rob Clark <robdclark@gmail.com>
> Reviewed-by: Rob Clark <robdclark@gmail.com>

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

> ---
>
> Changes in v3: None
> Changes in v2: None
>
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 86 ++++++++++++++++-----------
> 1 file changed, 52 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index d5990a0947b9..48fb4dc72e1c 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -530,6 +530,46 @@ static unsigned int ti_sn_get_max_lanes(struct ti_sn_bridge *pdata)
> return data & DP_LANE_COUNT_MASK;
> }
>
> +static int ti_sn_link_training(struct ti_sn_bridge *pdata)
> +{
> + unsigned int val;
> + int ret;
> +
> + /* set dp clk frequency value */
> + ti_sn_bridge_set_dp_rate(pdata);
> +
> + /* enable DP PLL */
> + regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 1);
> +
> + ret = regmap_read_poll_timeout(pdata->regmap, SN_DPPLL_SRC_REG, val,
> + val & DPPLL_SRC_DP_PLL_LOCK, 1000,
> + 50 * 1000);
> + if (ret) {
> + DRM_ERROR("DP_PLL_LOCK polling failed (%d)\n", ret);
> + goto exit;
> + }
> +
> + /* Semi auto link training mode */
> + regmap_write(pdata->regmap, SN_ML_TX_MODE_REG, 0x0A);
> + ret = regmap_read_poll_timeout(pdata->regmap, SN_ML_TX_MODE_REG, val,
> + val == ML_TX_MAIN_LINK_OFF ||
> + val == ML_TX_NORMAL_MODE, 1000,
> + 500 * 1000);
> + if (ret) {
> + DRM_ERROR("Training complete polling failed (%d)\n", ret);
> + } else if (val == ML_TX_MAIN_LINK_OFF) {
> + DRM_ERROR("Link training failed, link is off\n");
> + ret = -EIO;
> + }
> +
> +exit:
> + /* Disable the PLL if we failed */
> + if (ret)
> + regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 0);
> +
> + return ret;
> +}
> +
> static void ti_sn_bridge_enable(struct drm_bridge *bridge)
> {
> struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
> @@ -555,29 +595,8 @@ static void ti_sn_bridge_enable(struct drm_bridge *bridge)
> regmap_update_bits(pdata->regmap, SN_DSI_LANES_REG,
> CHA_DSI_LANES_MASK, val);
>
> - /* Set the DP output format (18 bpp or 24 bpp) */
> - val = (ti_sn_bridge_get_bpp(pdata) == 18) ? BPP_18_RGB : 0;
> - regmap_update_bits(pdata->regmap, SN_DATA_FORMAT_REG, BPP_18_RGB, val);
> -
> - /* DP lane config */
> - val = DP_NUM_LANES(min(pdata->dp_lanes, 3));
> - regmap_update_bits(pdata->regmap, SN_SSC_CONFIG_REG, DP_NUM_LANES_MASK,
> - val);
> -
> - /* set dsi/dp clk frequency value */
> + /* set dsi clk frequency value */
> ti_sn_bridge_set_dsi_rate(pdata);
> - ti_sn_bridge_set_dp_rate(pdata);
> -
> - /* enable DP PLL */
> - regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 1);
> -
> - ret = regmap_read_poll_timeout(pdata->regmap, SN_DPPLL_SRC_REG, val,
> - val & DPPLL_SRC_DP_PLL_LOCK, 1000,
> - 50 * 1000);
> - if (ret) {
> - DRM_ERROR("DP_PLL_LOCK polling failed (%d)\n", ret);
> - return;
> - }
>
> /**
> * The SN65DSI86 only supports ASSR Display Authentication method and
> @@ -588,19 +607,18 @@ static void ti_sn_bridge_enable(struct drm_bridge *bridge)
> drm_dp_dpcd_writeb(&pdata->aux, DP_EDP_CONFIGURATION_SET,
> DP_ALTERNATE_SCRAMBLER_RESET_ENABLE);
>
> - /* Semi auto link training mode */
> - regmap_write(pdata->regmap, SN_ML_TX_MODE_REG, 0x0A);
> - ret = regmap_read_poll_timeout(pdata->regmap, SN_ML_TX_MODE_REG, val,
> - val == ML_TX_MAIN_LINK_OFF ||
> - val == ML_TX_NORMAL_MODE, 1000,
> - 500 * 1000);
> - if (ret) {
> - DRM_ERROR("Training complete polling failed (%d)\n", ret);
> - return;
> - } else if (val == ML_TX_MAIN_LINK_OFF) {
> - DRM_ERROR("Link training failed, link is off\n");
> + /* Set the DP output format (18 bpp or 24 bpp) */
> + val = (ti_sn_bridge_get_bpp(pdata) == 18) ? BPP_18_RGB : 0;
> + regmap_update_bits(pdata->regmap, SN_DATA_FORMAT_REG, BPP_18_RGB, val);
> +
> + /* DP lane config */
> + val = DP_NUM_LANES(min(pdata->dp_lanes, 3));
> + regmap_update_bits(pdata->regmap, SN_SSC_CONFIG_REG, DP_NUM_LANES_MASK,
> + val);
> +
> + ret = ti_sn_link_training(pdata);
> + if (ret)
> return;
> - }
>
> /* config video parameters */
> ti_sn_bridge_set_video_timings(pdata);
> --
> 2.24.1.735.g03f4e72817-goog
>