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Message-ID: <c747c38ecd4a52ad51021cc0cb5ce9854b7378d3.camel@pengutronix.de>
Date: Wed, 17 May 2023 15:06:26 +0200
From: Lucas Stach <l.stach@...gutronix.de>
To: Adam Ford <aford173@...il.com>, dri-devel@...ts.freedesktop.org
Cc: aford@...conembedded.com, Chen-Yu Tsai <wenst@...omium.org>,
Frieder Schrempf <frieder.schrempf@...tron.de>,
Michael Walle <michael@...le.cc>,
Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Robert Foss <rfoss@...nel.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>,
Jernej Skrabec <jernej.skrabec@...il.com>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Inki Dae <inki.dae@...sung.com>,
Jagan Teki <jagan@...rulasolutions.com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Marek Vasut <marex@...x.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V6 5/6] drm: bridge: samsung-dsim: Dynamically configure
DPHY timing
Am Montag, dem 15.05.2023 um 18:57 -0500 schrieb Adam Ford:
> The DPHY timings are currently hard coded. Since the input
> clock can be variable, the phy timings need to be variable
> too. To facilitate this, we need to cache the hs_clock
> based on what is generated from the PLL.
>
> The phy_mipi_dphy_get_default_config_for_hsclk function
> configures the DPHY timings in pico-seconds, and a small macro
> converts those timings into clock cycles based on the hs_clk.
>
I'm not going apply a review tag to a patch where I contributed myself,
but FWIW this looks good to me.
> Signed-off-by: Adam Ford <aford173@...il.com>
> Signed-off-by: Lucas Stach <l.stach@...gutronix.de>
> Tested-by: Chen-Yu Tsai <wenst@...omium.org>
> Tested-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> Tested-by: Michael Walle <michael@...le.cc>
> ---
> drivers/gpu/drm/bridge/samsung-dsim.c | 57 +++++++++++++++++++++++----
> include/drm/bridge/samsung-dsim.h | 1 +
> 2 files changed, 51 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index 08266303c261..3944b7cfbbdf 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -218,6 +218,8 @@
>
> #define OLD_SCLK_MIPI_CLK_NAME "pll_clk"
>
> +#define PS_TO_CYCLE(ps, hz) DIV64_U64_ROUND_CLOSEST(((ps) * (hz)), 1000000000000ULL)
> +
> static const char *const clk_names[5] = {
> "bus_clk",
> "sclk_mipi",
> @@ -651,6 +653,8 @@ static unsigned long samsung_dsim_set_pll(struct samsung_dsim *dsi,
> reg = samsung_dsim_read(dsi, DSIM_STATUS_REG);
> } while ((reg & DSIM_PLL_STABLE) == 0);
>
> + dsi->hs_clock = fout;
> +
> return fout;
> }
>
> @@ -698,13 +702,46 @@ static void samsung_dsim_set_phy_ctrl(struct samsung_dsim *dsi)
> const struct samsung_dsim_driver_data *driver_data = dsi->driver_data;
> const unsigned int *reg_values = driver_data->reg_values;
> u32 reg;
> + struct phy_configure_opts_mipi_dphy cfg;
> + int clk_prepare, lpx, clk_zero, clk_post, clk_trail;
> + int hs_exit, hs_prepare, hs_zero, hs_trail;
> + unsigned long long byte_clock = dsi->hs_clock / 8;
>
> if (driver_data->has_freqband)
> return;
>
> + phy_mipi_dphy_get_default_config_for_hsclk(dsi->hs_clock,
> + dsi->lanes, &cfg);
> +
> + /*
> + * TODO:
> + * The tech reference manual for i.MX8M Mini/Nano/Plus
> + * doesn't state what the definition of the PHYTIMING
> + * bits are beyond their address and bit position.
> + * After reviewing NXP's downstream code, it appears
> + * that the various PHYTIMING registers take the number
> + * of cycles and use various dividers on them. This
> + * calculation does not result in an exact match to the
> + * downstream code, but it is very close, and it appears
> + * to sync at a variety of resolutions. If someone
> + * can get a more accurate mathematical equation needed
> + * for these registers, this should be updated.
> + */
> +
> + lpx = PS_TO_CYCLE(cfg.lpx, byte_clock);
> + hs_exit = PS_TO_CYCLE(cfg.hs_exit, byte_clock);
> + clk_prepare = PS_TO_CYCLE(cfg.clk_prepare, byte_clock);
> + clk_zero = PS_TO_CYCLE(cfg.clk_zero, byte_clock);
> + clk_post = PS_TO_CYCLE(cfg.clk_post, byte_clock);
> + clk_trail = PS_TO_CYCLE(cfg.clk_trail, byte_clock);
> + hs_prepare = PS_TO_CYCLE(cfg.hs_prepare, byte_clock);
> + hs_zero = PS_TO_CYCLE(cfg.hs_zero, byte_clock);
> + hs_trail = PS_TO_CYCLE(cfg.hs_trail, byte_clock);
> +
> /* B D-PHY: D-PHY Master & Slave Analog Block control */
> reg = reg_values[PHYCTRL_ULPS_EXIT] | reg_values[PHYCTRL_VREG_LP] |
> reg_values[PHYCTRL_SLEW_UP];
> +
> samsung_dsim_write(dsi, DSIM_PHYCTRL_REG, reg);
>
> /*
> @@ -712,7 +749,9 @@ static void samsung_dsim_set_phy_ctrl(struct samsung_dsim *dsi)
> * T HS-EXIT: Time that the transmitter drives LP-11 following a HS
> * burst
> */
> - reg = reg_values[PHYTIMING_LPX] | reg_values[PHYTIMING_HS_EXIT];
> +
> + reg = DSIM_PHYTIMING_LPX(lpx) | DSIM_PHYTIMING_HS_EXIT(hs_exit);
> +
> samsung_dsim_write(dsi, DSIM_PHYTIMING_REG, reg);
>
> /*
> @@ -728,10 +767,11 @@ static void samsung_dsim_set_phy_ctrl(struct samsung_dsim *dsi)
> * T CLK-TRAIL: Time that the transmitter drives the HS-0 state after
> * the last payload clock bit of a HS transmission burst
> */
> - reg = reg_values[PHYTIMING_CLK_PREPARE] |
> - reg_values[PHYTIMING_CLK_ZERO] |
> - reg_values[PHYTIMING_CLK_POST] |
> - reg_values[PHYTIMING_CLK_TRAIL];
> +
> + reg = DSIM_PHYTIMING1_CLK_PREPARE(clk_prepare) |
> + DSIM_PHYTIMING1_CLK_ZERO(clk_zero) |
> + DSIM_PHYTIMING1_CLK_POST(clk_post) |
> + DSIM_PHYTIMING1_CLK_TRAIL(clk_trail);
>
> samsung_dsim_write(dsi, DSIM_PHYTIMING1_REG, reg);
>
> @@ -744,8 +784,11 @@ static void samsung_dsim_set_phy_ctrl(struct samsung_dsim *dsi)
> * T HS-TRAIL: Time that the transmitter drives the flipped differential
> * state after last payload data bit of a HS transmission burst
> */
> - reg = reg_values[PHYTIMING_HS_PREPARE] | reg_values[PHYTIMING_HS_ZERO] |
> - reg_values[PHYTIMING_HS_TRAIL];
> +
> + reg = DSIM_PHYTIMING2_HS_PREPARE(hs_prepare) |
> + DSIM_PHYTIMING2_HS_ZERO(hs_zero) |
> + DSIM_PHYTIMING2_HS_TRAIL(hs_trail);
> +
> samsung_dsim_write(dsi, DSIM_PHYTIMING2_REG, reg);
> }
>
> diff --git a/include/drm/bridge/samsung-dsim.h b/include/drm/bridge/samsung-dsim.h
> index a1a5b2b89a7a..d9d431e3b65a 100644
> --- a/include/drm/bridge/samsung-dsim.h
> +++ b/include/drm/bridge/samsung-dsim.h
> @@ -93,6 +93,7 @@ struct samsung_dsim {
>
> u32 pll_clk_rate;
> u32 burst_clk_rate;
> + u32 hs_clock;
> u32 esc_clk_rate;
> u32 lanes;
> u32 mode_flags;
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