[PATCH v9 10/18] drm: bridge: samsung-dsim: Init exynos host for first DSI transfer
Marek Szyprowski
m.szyprowski at samsung.com
Tue Dec 13 06:54:54 PST 2022
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.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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