Re: [PATCH v9 05/13] drm/mediatek: mtk_dsi: Enable interrupt at component bind time

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

On 11/4/26 19:56, Roman Vivchar wrote:
> On Wednesday, September 16th, 2026 at 2:08 PM, AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> wrote:
> 
>> Having the DSI interrupt enabled before actually binding the DSI
>> component to the display controller driver is both useless and
>> dangerous: the main purpose of this interrupt is to signal CMD
>> done, LP RX data ready, or VideoMode done, or to reset the HW
>> engine if this doesn't come.
>>
>> Should this interrupt come too late (during probe), the HW will
>> be reset only at the next occurrence of a timeout, which slows
>> down boot and may render artifacts to the DSI display.
>>
>> Moreover, clearing the DSI interrupt while the display controller
>> is not ready yet, may result in an interrupt storm.
>>
>> In order to prevent this from happening, request the interrupt
>> with IRQF_NO_AUTOEN, and enable it only when binding DSI to its
>> display controller component master.
>>
>> Reviewed-by: CK Hu <ck.hu@mediatek.com>
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> 
> This was necessary on mt6595, otherwise it would get stuck.
> 

Yep, I guess it was getting stuck before this because your platform's bootloader
has continuous splash functionality and leaves it on while booting Linux, right?

Just a curiosity... ;-)

Cheers,
Angelo

> Acked-by: Roman Vivchar <rva333@protonmail.com>
> Tested-by: Roman Vivchar <rva333@protonmail.com> # mt6595, mt6768
> 
>> ---
>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 24 +++++++++++++-----------
>>   1 file changed, 13 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> index 28ba532210ff..6ac6daa61e68 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> @@ -225,6 +225,7 @@ struct mtk_dsi {
>>   	int refcount;
>>   	bool enabled;
>>   	bool lanes_ready;
>> +	int irq;
>>   	u32 irq_data;
>>   	wait_queue_head_t irq_wait_queue;
>>   	const struct mtk_dsi_driver_data *driver_data;
>> @@ -1101,6 +1102,8 @@ static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>>   		return ret;
>>   	}
>>
>> +	enable_irq(dsi->irq);
>> +
>>   	return 0;
>>   }
>>
>> @@ -1109,6 +1112,8 @@ static void mtk_dsi_unbind(struct device *dev, struct device *master,
>>   {
>>   	struct mtk_dsi *dsi = dev_get_drvdata(dev);
>>
>> +	disable_irq(dsi->irq);
>> +
>>   	drm_encoder_cleanup(&dsi->encoder);
>>   }
>>
>> @@ -1342,7 +1347,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>   {
>>   	struct mtk_dsi *dsi;
>>   	struct device *dev = &pdev->dev;
>> -	int irq_num;
>>   	int ret;
>>
>>   	dsi = devm_drm_bridge_alloc(dev, struct mtk_dsi, bridge,
>> @@ -1375,9 +1379,9 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>   	if (IS_ERR(dsi->phy))
>>   		return dev_err_probe(dev, PTR_ERR(dsi->phy), "Failed to get MIPI-DPHY\n");
>>
>> -	irq_num = platform_get_irq(pdev, 0);
>> -	if (irq_num < 0)
>> -		return irq_num;
>> +	dsi->irq = platform_get_irq(pdev, 0);
>> +	if (dsi->irq < 0)
>> +		return dsi->irq;
>>
>>   	dsi->host.ops = &mtk_dsi_ops;
>>   	dsi->host.dev = dev;
>> @@ -1386,17 +1390,15 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>
>>   	platform_set_drvdata(pdev, dsi);
>>
>> +	ret = devm_request_irq(&pdev->dev, dsi->irq, mtk_dsi_irq,
>> +			       IRQF_NO_AUTOEN, dev_name(&pdev->dev), dsi);
>> +	if (ret)
>> +		return dev_err_probe(&pdev->dev, ret, "Failed to request DSI irq\n");
>> +
>>   	ret = mipi_dsi_host_register(&dsi->host);
>>   	if (ret < 0)
>>   		return dev_err_probe(dev, ret, "Failed to register DSI host\n");
>>
>> -	ret = devm_request_irq(&pdev->dev, irq_num, mtk_dsi_irq,
>> -			       IRQF_TRIGGER_NONE, dev_name(&pdev->dev), dsi);
>> -	if (ret) {
>> -		mipi_dsi_host_unregister(&dsi->host);
>> -		return dev_err_probe(&pdev->dev, ret, "Failed to request DSI irq\n");
>> -	}
>> -
>>   	dsi->bridge.of_node = dev->of_node;
>>   	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>>
>> --
>> 2.55.0
>>
>>
>>