[PATCH v2 05/12] drm: bridge: samsung-dsim: Add DSI init in bridge pre_enable()

[Marek Szyprowski]

On 11.05.2022 17:02, Marek Szyprowski wrote:
> On 04.05.2022 13:40, Jagan Teki wrote:
>> Host transfer() in DSI master will invoke only when the DSI commands
>> are sent from DSI devices like DSI Panel or DSI bridges and this
>> host transfer wouldn't invoke for I2C-based-DSI bridge drivers.
>>
>> Handling DSI host initialization in transfer calls misses the
>> controller setup for I2C configured DSI bridges.
>>
>> This patch adds the DSI initialization from transfer to bridge
>> pre_enable as the bridge pre_enable API is invoked by core as
>> it is common across all classes of DSI device drivers.
>>
>> v2:
>> * check initialized state in samsung_dsim_init
>>
>> v1:
>> * keep DSI init in host transfer
>>
>> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
>
> This doesn't work with Exynos DSI and DSI panels. Here is a bit more 
> detailed explanation and my solution for this:
>
> https://lore.kernel.org/all/e96197f9-948a-997e-5453-9f9d179b5f5a@samsung.com/ 
>


I wonder if your modification works on i.MX8MM with a pure DSI-based 
panel/bridge. In your tree I only see that you have tested it with the 
i2c-controlled DSI-to-LVDS converter.


After the comments from the above mentioned thread I've reworked the 
initialization again. It looks that the ultimate solution for both 
worlds is to call samsung_dsim_init() twice, once in pre_enable, then 
before the first host_transfer, see 
https://github.com/mszyprow/linux/tree/v5.18-next-20220511-dsi-rework-v2

This way at least it works fine on all my Exynos based test boards.

>> ---
>>   drivers/gpu/drm/bridge/samsung-dsim.c | 18 ++++++++++++------
>>   1 file changed, 12 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c 
>> b/drivers/gpu/drm/bridge/samsung-dsim.c
>> index 60dc863113a0..b9361af5ef2d 100644
>> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
>> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
>> @@ -1259,6 +1259,9 @@ static int samsung_dsim_init(struct 
>> samsung_dsim *dsi)
>>   {
>>       const struct samsung_dsim_driver_data *driver_data = 
>> dsi->driver_data;
>>   +    if (dsi->state & DSIM_STATE_INITIALIZED)
>> +        return 0;
>> +
>>       samsung_dsim_reset(dsi);
>>       samsung_dsim_enable_irq(dsi);
>>   @@ -1271,6 +1274,8 @@ static int samsung_dsim_init(struct 
>> samsung_dsim *dsi)
>>       samsung_dsim_set_phy_ctrl(dsi);
>>       samsung_dsim_init_link(dsi);
>>   +    dsi->state |= DSIM_STATE_INITIALIZED;
>> +
>>       return 0;
>>   }
>>   @@ -1290,6 +1295,10 @@ static void 
>> samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge,
>>       }
>>         dsi->state |= DSIM_STATE_ENABLED;
>> +
>> +    ret = samsung_dsim_init(dsi);
>> +    if (ret)
>> +        return;
>>   }
>>     static void samsung_dsim_atomic_enable(struct drm_bridge *bridge,
>> @@ -1464,12 +1473,9 @@ static ssize_t 
>> samsung_dsim_host_transfer(struct mipi_dsi_host *host,
>>       if (!(dsi->state & DSIM_STATE_ENABLED))
>>           return -EINVAL;
>>   -    if (!(dsi->state & DSIM_STATE_INITIALIZED)) {
>> -        ret = samsung_dsim_init(dsi);
>> -        if (ret)
>> -            return ret;
>> -        dsi->state |= DSIM_STATE_INITIALIZED;
>> -    }
>> +    ret = samsung_dsim_init(dsi);
>> +    if (ret)
>> +        return ret;
>>         ret = mipi_dsi_create_packet(&xfer.packet, msg);
>>       if (ret < 0)
>
> Best regards

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland