Re: [PATCH v2 1/2] drm: bridge: samsung-dsim: Fix i.MX8M enable flow to meet spec
From: Alexander Stein
Date: Thu Jul 13 2023 - 02:22:13 EST
Hi,
Am Donnerstag, 13. Juli 2023, 00:34:47 CEST schrieb Tim Harvey:
> On Wed, May 3, 2023 at 9:33 AM Frieder Schrempf <frieder@xxxxxxx> wrote:
> > From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> >
> > According to the documentation [1] the proper enable flow is:
> >
> > 1. Enable DSI link and keep data lanes in LP-11 (stop state)
> > 2. Disable stop state to bring data lanes into HS mode
> >
> > Currently we do this all at once within enable(), which doesn't
> > allow to meet the requirements of some downstream bridges.
> >
> > To fix this we now enable the DSI in pre_enable() and force it
> > into stop state using the FORCE_STOP_STATE bit in the ESCMODE
> > register until enable() is called where we reset the bit.
> >
> > We currently do this only for i.MX8M as Exynos uses a different
> > init flow where samsung_dsim_init() is called from
> > samsung_dsim_host_transfer().
> >
> > [1]
> > https://docs.kernel.org/gpu/drm-kms-helpers.html#mipi-dsi-bridge-operatio
> > n
> >
> > Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> > ---
> > Changes for v2:
> > * Drop RFC
> > ---
> >
> > drivers/gpu/drm/bridge/samsung-dsim.c | 25 +++++++++++++++++++++++--
> > 1 file changed, 23 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
> > b/drivers/gpu/drm/bridge/samsung-dsim.c index e0a402a85787..9775779721d9
> > 100644
> > --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> > +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> > @@ -859,6 +859,10 @@ static int samsung_dsim_init_link(struct samsung_dsim
> > *dsi)>
> > reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> > reg &= ~DSIM_STOP_STATE_CNT_MASK;
> > reg |=
> > DSIM_STOP_STATE_CNT(driver_data->reg_values[STOP_STATE_CNT]);
> >
> > +
> > + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type))
> > + reg |= DSIM_FORCE_STOP_STATE;
> > +
> >
> > samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
> >
> > reg = DSIM_BTA_TIMEOUT(0xff) | DSIM_LPDR_TIMEOUT(0xffff);
> >
> > @@ -1340,6 +1344,9 @@ static void samsung_dsim_atomic_pre_enable(struct
> > drm_bridge *bridge,>
> > ret = samsung_dsim_init(dsi);
> > if (ret)
> >
> > return;
> >
> > +
> > + samsung_dsim_set_display_mode(dsi);
> > + samsung_dsim_set_display_enable(dsi, true);
> >
> > }
> >
> > }
> >
> > @@ -1347,9 +1354,16 @@ static void samsung_dsim_atomic_enable(struct
> > drm_bridge *bridge,>
> > struct drm_bridge_state
> > *old_bridge_state)
> >
> > {
> >
> > struct samsung_dsim *dsi = bridge_to_dsi(bridge);
> >
> > + u32 reg;
> >
> > - samsung_dsim_set_display_mode(dsi);
> > - samsung_dsim_set_display_enable(dsi, true);
> > + if (samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) {
> > + samsung_dsim_set_display_mode(dsi);
> > + samsung_dsim_set_display_enable(dsi, true);
> > + } else {
> > + reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> > + reg &= ~DSIM_FORCE_STOP_STATE;
> > + samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
> > + }
> >
> > dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
> >
> > }
> >
> > @@ -1358,10 +1372,17 @@ static void samsung_dsim_atomic_disable(struct
> > drm_bridge *bridge,>
> > struct drm_bridge_state
> > *old_bridge_state)
> >
> > {
> >
> > struct samsung_dsim *dsi = bridge_to_dsi(bridge);
> >
> > + u32 reg;
> >
> > if (!(dsi->state & DSIM_STATE_ENABLED))
> >
> > return;
> >
> > + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) {
> > + reg = samsung_dsim_read(dsi, DSIM_ESCMODE_REG);
> > + reg |= DSIM_FORCE_STOP_STATE;
> > + samsung_dsim_write(dsi, DSIM_ESCMODE_REG, reg);
> > + }
> > +
> >
> > dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE;
> >
> > }
> >
> > --
> > 2.40.0
>
> Hi Frieder,
>
> I found this patch to break mipi-dsi display on my board which has:
> - FocalTech FT5406 10pt touch controller (with no interrupt)
> - Powertip PH800480T013-IDF02 compatible panel
> - Toshiba TC358762 compatible DSI to DBI bridge
> - ATTINY based regulator used for backlight controller and panel enable
>
> I enable this via a dt overlay in a pending patch
> imx8mm-venice-gw72xx-0x-rpidsi.dtso [1] which works on 6.4 but not
> 6.5-rc1 which has this patch.
>
> The issue appears as:
> [ 6.110585] samsung-dsim 32e60000.dsi: xfer timed out: 29 06 00 00
> 64 01 05 00 00 00
> [ 6.326588] tc358762 32e60000.dsi.0: error initializing bridge (-110)
>
> Instead of
> [ 1.011729] samsung-dsim 32e10000.dsi: supply vddcore not found,
> using dummy regulator
> [ 1.019829] samsung-dsim 32e10000.dsi: supply vddio not found,
> using dummy regulator
> [ 5.649928] samsung-dsim 32e10000.dsi:
> [drm:samsung_dsim_host_attach] Attached tc358762 device
>
> I'm curious what board/panel were you needing this for and do you have
> any ideas why it broke my setup?
>
> I'm also curious what board/panel Alexander tested this with and if
> Adam or Jagan (or others) have tested this with their hardware?
I tested this with imx8mm and ti,sn65dsi83 DSI-LVDS bridge [1]. I don't know
anything about tc358762, but I was trying to get tc9595 (DSI-DP bridge)
running on a imx8mp based board. One of my problems was that the bridge
requires LP-11 before reset release, which is currently not given using
samsung-dsim and tc358767 driver. Maybe this is the case for you as well.
AFAICS there is a lot more to do to get this running properly.
Best regards,
Alexander
[1] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/
arch/arm64/boot/dts/freescale/imx8mp-tqma8mpql-mba8mpxl-lvds.dtso
> best regards,
>
> Tim
> [1]
> https://patchwork.kernel.org/project/linux-arm-kernel/patch/20230711221124.
> 2127186-1-tharvey@xxxxxxxxxxxxx/
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