[PATCH v9 10/18] drm: bridge: samsung-dsim: Init exynos host for first DSI transfer
Marek Szyprowski
m.szyprowski at samsung.com
Wed Dec 14 00:04:43 PST 2022
On 14.12.2022 06:33, Jagan Teki wrote:
> On Tue, Dec 13, 2022 at 9:11 PM Marek Szyprowski
> <m.szyprowski at samsung.com> wrote:
>> On 13.12.2022 16:15, Jagan Teki wrote:
>>> 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
>> It doesn't need the DSIM_STATE_REINITIALIZED flag because the
>> initialization is done only once - in pre_enable for non-Exynos case and
>> on the first transfer for the Exynos case. In both cases the same flag
>> (DSIM_STATE_INITIALIZED) is used.
>>
>> See the attached patch.
> Thanks, I have included the changes and added your authorship as well.
>
> Please test this final version and let me know if you have any comments.
> https://gitlab.com/openedev/kernel/-/commits/imx8mm-dsi-v10
Fine for me.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
More information about the linux-arm-kernel
mailing list