Re: [Freedreno] [PATCH] drm/msm/dsi: do not install irq handler before power up the host

[abhinavk@codeaurora.org]

On 2021-09-21 09:22, Dmitry Baryshkov wrote:
> The DSI host might be left in some state by the bootloader. If this
> state generates an IRQ, it might hang the system by holding the
> interrupt line before the driver sets up the DSI host to the known
> state.
> 
> Move the request/free_irq calls into msm_dsi_host_power_on/_off calls,
> so that we can be sure that the interrupt is delivered when the host is
> in the known state.
> 
> Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

This is a valid change and we have seen interrupt storms in downstream 
happening
when like you said the bootloader leaves the DSI host in unknown state.
Just one question below.

> ---
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c
> b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index e269df285136..cd842347a6b1 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -1951,15 +1951,6 @@ int msm_dsi_host_modeset_init(struct 
> mipi_dsi_host *host,
>  		return ret;
>  	}
> 
> -	ret = devm_request_irq(&pdev->dev, msm_host->irq,
> -			dsi_host_irq, IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> -			"dsi_isr", msm_host);
> -	if (ret < 0) {
> -		DRM_DEV_ERROR(&pdev->dev, "failed to request IRQ%u: %d\n",
> -				msm_host->irq, ret);
> -		return ret;
> -	}
> -
>  	msm_host->dev = dev;
>  	ret = cfg_hnd->ops->tx_buf_alloc(msm_host, SZ_4K);
>  	if (ret) {
> @@ -2413,6 +2404,16 @@ int msm_dsi_host_power_on(struct mipi_dsi_host 
> *host,
>  	if (msm_host->disp_en_gpio)
>  		gpiod_set_value(msm_host->disp_en_gpio, 1);
> 
> +	ret = devm_request_irq(&msm_host->pdev->dev, msm_host->irq,
> +			dsi_host_irq, IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
> +			"dsi_isr", msm_host);
> +	if (ret < 0) {
> +		DRM_DEV_ERROR(&msm_host->pdev->dev, "failed to request IRQ%u: %d\n",
> +				msm_host->irq, ret);
> +		return ret;
> +	}
> +
> +

Do you want to move this to msm_dsi_host_enable()?
So without the controller being enabled it is still in unknown state?
Also do you want to do this after dsi0 and dsi1 are initialized to 
account for
dual dsi cases?

>  	msm_host->power_on = true;
>  	mutex_unlock(&msm_host->dev_mutex);
> 
> @@ -2439,6 +2440,8 @@ int msm_dsi_host_power_off(struct mipi_dsi_host 
> *host)
>  		goto unlock_ret;
>  	}
> 
> +	devm_free_irq(&msm_host->pdev->dev, msm_host->irq, msm_host);
> +
>  	dsi_ctrl_config(msm_host, false, NULL, NULL);
> 
>  	if (msm_host->disp_en_gpio)