[PATCH v9 10/18] drm: bridge: samsung-dsim: Init exynos host for first DSI transfer
Jagan Teki
jagan at amarulasolutions.com
Tue Dec 13 06:18:49 PST 2022
On Tue, Dec 13, 2022 at 7:31 PM Marek Szyprowski
<m.szyprowski at samsung.com> wrote:
>
> On 13.12.2022 13:20, Marek Szyprowski wrote:
> > On 13.12.2022 11:40, Jagan Teki wrote:
> >> On Tue, Dec 13, 2022 at 2:28 PM Marek Szyprowski
> >> <m.szyprowski at samsung.com> wrote:
> >>> On 12.12.2022 16:33, Jagan Teki wrote:
> >>>
> >>> On Mon, Dec 12, 2022 at 8:52 PM Marek Szyprowski
> >>> <m.szyprowski at samsung.com> wrote:
> >>>
> >>> On 12.12.2022 09:43, Marek Szyprowski wrote:
> >>>
> >>> On 12.12.2022 09:32, Jagan Teki wrote:
> >>>
> >>> On Mon, Dec 12, 2022 at 1:56 PM Marek Szyprowski
> >>> <m.szyprowski at samsung.com> wrote:
> >>>
> >>> Hi Jagan,
> >>>
> >>> On 09.12.2022 16:23, Jagan Teki wrote:
> >>>
> >>> The existing drm panels and bridges in Exynos required host
> >>> initialization during the first DSI command transfer even though
> >>> the initialization was done before.
> >>>
> >>> This host reinitialization is handled via DSIM_STATE_REINITIALIZED
> >>> flag and triggers from host transfer.
> >>>
> >>> Do this exclusively for Exynos.
> >>>
> >>> Initial logic is derived from Marek Szyprowski changes.
> >>>
> >>> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> >>> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
> >>> ---
> >>> Changes from v9:
> >>> - derived from v8
> >>> - added comments
> >>>
> >>> drivers/gpu/drm/bridge/samsung-dsim.c | 15 ++++++++++++++-
> >>> include/drm/bridge/samsung-dsim.h | 5 +++--
> >>> 2 files changed, 17 insertions(+), 3 deletions(-)
> >>>
> >>> The following chunk is missing compared to v8:
> >>>
> >>> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> b/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> index 6e9ad955ebd3..6a9403cb92ae 100644
> >>> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> @@ -1315,7 +1315,9 @@ static int samsung_dsim_init(struct samsung_dsim
> >>> *dsi, unsigned int flag)
> >>> return 0;
> >>>
> >>> samsung_dsim_reset(dsi);
> >>> - samsung_dsim_enable_irq(dsi);
> >>> +
> >>> + if (!(dsi->state & DSIM_STATE_INITIALIZED))
> >>> + samsung_dsim_enable_irq(dsi);
> >>>
> >>> Is this really required? does it make sure that the IRQ does not
> >>> enable twice?
> >>>
> >>> That's what that check does. Without the 'if (!(dsi->state &
> >>> DSIM_STATE_INITIALIZED))' check, the irqs will be enabled twice (first
> >>> from pre_enable, then from the first transfer), what leads to a
> >>> warning from irq core.
> >>>
> >>> I've just noticed that we also would need to clear the
> >>> DSIM_STATE_REINITIALIZED flag in dsim_suspend.
> >>>
> >>> However I've found that a bit simpler patch would keep the current code
> >>> flow for Exynos instead of this reinitialization hack. This can be
> >>> applied on the "[PATCH v9 09/18] drm: bridge: samsung-dsim: Add host
> >>> init in pre_enable" patch:
> >>>
> >>> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> b/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> index 0b2e52585485..acc95c61ae45 100644
> >>> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> >>> @@ -1291,9 +1291,11 @@ static void
> >>> samsung_dsim_atomic_pre_enable(struct
> >>> drm_bridge *bridge,
> >>>
> >>> dsi->state |= DSIM_STATE_ENABLED;
> >>>
> >>> - ret = samsung_dsim_init(dsi, DSIM_STATE_INITIALIZED);
> >>> - if (ret)
> >>> - return;
> >>> + if (!samsung_dsim_hw_is_exynos(dsi->plat_data->hw_type)) {
> >>> + ret = samsung_dsim_init(dsi, DSIM_STATE_INITIALIZED);
> >>> + if (ret)
> >>> + return;
> >>> + }
> >>>
> >>> Sorry, I don't understand this. Does it mean Exynos doesn't need to
> >>> init host in pre_enable? If I remember correctly even though the host
> >>> is initialized it has to reinitialize during the first transfer - This
> >>> is what the Exynos requirement is. Please correct or explain here.
> >>>
> >>> This is a matter of enabling power regulator(s) in the right order
> >>> and doing the host initialization in the right moment. It was never
> >>> a matter of re-initialization. See the current code for the
> >>> reference (it uses the same approach as my above change). I've
> >>> already explained that here:
> >>>
> >>> https://lore.kernel.org/all/e96197f9-948a-997e-5453-9f9d179b5f5a@samsung.com/
> >>>
> >>>
> >>> If you would like to see the exact proper moment of the dsi host
> >>> initialization on the Exynos see the code here:
> >>>
> >>> https://protect2.fireeye.com/v1/url?k=5dc33900-0258001f-5dc2b24f-000babdfecba-f7c1a2a1905c83ca&q=1&e=f086bfdb-9055-48bd-b9c2-5dffb6c0d558&u=https%3A%2F%2Fgithub.com%2Fmszyprow%2Flinux%2Ftree%2Fv5.18-next-20220511-dsi-rework
> >>> and patches adding mipi_dsi_host_init() to panel/bridge drivers.
> >> As I said before, the downstream bridge needs an explicit call to host
> >> init via mipi_dsi_host_init - this is indeed not a usual use-case
> >> scenario. Let's handle this with a REINIT fix and see if we can update
> >> this later to handle both scenarios.
> >>
> >> Would you please test this repo, I have included all.
> >>
> >> https://gitlab.com/openedev/kernel/-/commits/imx8mm-dsi-v10
> >
> > This doesn't work on TM2e board. Give me some time to find why...
> >
> The following change is missing in "drm: bridge: Generalize Exynos-DSI
> driver into a Samsung DSIM bridge" patch:
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
> b/drivers/gpu/drm/bridge/samsung-dsim.c
> index 1dbff2bee93f..81828b5ee0ac 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1745,6 +1745,7 @@ int samsung_dsim_probe(struct platform_device *pdev)
> dsi->bridge.funcs = &samsung_dsim_bridge_funcs;
> dsi->bridge.of_node = dev->of_node;
> dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
> + dsi->bridge.pre_enable_prev_first = true;
Can you check this and confirm, I keep this in exynos side.
https://gitlab.com/openedev/kernel/-/commit/ccb02df7a313fdf91d8e116b0ec3d6c945fbb6fd#c93f0ce4d81b854fbde970e341fb307f1be78c16_1865_189
>
> /* DE_LOW: i.MX8M Mini/Nano LCDIF-DSIM glue logic inverts
> HS/VS/DE */
> if (dsi->plat_data->hw_type == DSIM_TYPE_IMX8MM)
>
>
> After adding the above, all my test platform works fine.
>
> BTW, I still think that it is worth replacing the "drm: exynos: dsi: Add
> host initialization in pre_enable" patch with the following simple
> change and propagate it to bridge/samsung-dsim.c:
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index fdaf514b39f2..071b74d60dcb 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -254,6 +254,9 @@ struct exynos_dsi_transfer {
> #define DSIM_STATE_CMD_LPM BIT(2)
> #define DSIM_STATE_VIDOUT_AVAILABLE BIT(3)
>
> +#define exynos_dsi_hw_is_exynos(hw) \
> + ((hw) >= DSIM_TYPE_EXYNOS3250 && (hw) <= DSIM_TYPE_EXYNOS5433)
> +
> enum exynos_dsi_type {
> DSIM_TYPE_EXYNOS3250,
> DSIM_TYPE_EXYNOS4210,
> @@ -1344,6 +1347,9 @@ static int exynos_dsi_init(struct exynos_dsi *dsi)
> {
> const struct exynos_dsi_driver_data *driver_data =
> dsi->driver_data;
>
> + if (dsi->state & DSIM_STATE_INITIALIZED)
> + return 0;
> +
> exynos_dsi_reset(dsi);
> exynos_dsi_enable_irq(dsi);
>
> @@ -1356,6 +1362,8 @@ static int exynos_dsi_init(struct exynos_dsi *dsi)
> exynos_dsi_set_phy_ctrl(dsi);
> exynos_dsi_init_link(dsi);
>
> + dsi->state |= DSIM_STATE_INITIALIZED;
> +
> return 0;
> }
>
> @@ -1411,6 +1419,12 @@ static void exynos_dsi_atomic_pre_enable(struct
> drm_bridge *bridge,
> }
>
> dsi->state |= DSIM_STATE_ENABLED;
> +
> + if (!exynos_dsi_hw_is_exynos(dsi->plat_data->hw_type)) {
> + ret = exynos_dsi_init(dsi);
> + if (ret)
> + return;
> + }
> }
>
> static void exynos_dsi_atomic_enable(struct drm_bridge *bridge,
> @@ -1557,12 +1571,9 @@ static ssize_t exynos_dsi_host_transfer(struct
> mipi_dsi_host *host,
> if (!(dsi->state & DSIM_STATE_ENABLED))
> return -EINVAL;
>
> - if (!(dsi->state & DSIM_STATE_INITIALIZED)) {
> - ret = exynos_dsi_init(dsi);
> - if (ret)
> - return ret;
> - dsi->state |= DSIM_STATE_INITIALIZED;
> - }
> + ret = exynos_dsi_init(dsi);
> + if (ret)
> + return ret;
Below patch handling similar behavior by checking exynos hw_type at
exynos_dsi_init, isn't it? Please check and let me know if I missing
anything.
https://gitlab.com/openedev/kernel/-/commit/d19d491eef92b92e12a26265697274ce666eddb5
Jagan.
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