[PATCH v9 10/18] drm: bridge: samsung-dsim: Init exynos host for first DSI transfer
Jagan Teki
jagan at amarulasolutions.com
Tue Dec 13 15:15:40 UTC 2022
On Tue, Dec 13, 2022 at 8:24 PM Marek Szyprowski
<m.szyprowski at samsung.com> wrote:
>
> On 13.12.2022 15:18, Jagan Teki wrote:
> > 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
>
> This one is fine!
>
> >> /* 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
>
> You don't miss anything. Your version also works, but I just proposed a
> bit simpler code.
Do your changes don't need a DSIM_STATE_REINITIALIZED flag? would you
please share the change on top of this commit?
https://gitlab.com/openedev/kernel/-/commit/d19d491eef92b92e12a26265697274ce666eddb5
Jagan.
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