[PATCH v2 6/6] drm/bridge: cdns-mhdp8546: Fix the interrupt enable/disable

[Swapnil Kashinath Jakhade]

Hi Nikhil,

> -----Original Message-----
> From: Nikhil Devshatwar <nikhil.nd at ti.com>
> Sent: Monday, November 9, 2020 10:36 PM
> To: dri-devel at lists.freedesktop.org; Tomi Valkeinen
> <tomi.valkeinen at ti.com>
> Cc: Sekhar Nori <nsekhar at ti.com>; Laurent Pinchart
> <laurent.pinchart at ideasonboard.com>; Swapnil Kashinath Jakhade
> <sjakhade at cadence.com>; Yuti Suresh Amonkar <yamonkar at cadence.com>
> Subject: [PATCH v2 6/6] drm/bridge: cdns-mhdp8546: Fix the interrupt
> enable/disable
> 
> EXTERNAL MAIL
> 
> 
> When removing the tidss driver, there is a warning reported by kernel about
> an unhandled interrupt for mhdp driver.
> 
> [   43.238895] irq 31: nobody cared (try booting with the "irqpoll" option)
> ... [snipped backtrace]
> [   43.330735] handlers:
> [   43.333020] [<000000005367c4f9>] irq_default_primary_handler threaded
> [<000000007e02b601>]
> cdns_mhdp_irq_handler [cdns_mhdp8546]
> [   43.344607] Disabling IRQ #31
> 
> This happens because as part of cdns_mhdp_bridge_hpd_disable, driver
> tries to disable the interrupts. While disabling the SW_EVENT interrupts, it
> accidentally enables the MBOX interrupts, which are not handled by the
> driver.
> 
> Fix this with a read-modify-write to update only required bits.
> Do the same for enabling interrupts as well.
> 
> Signed-off-by: Nikhil Devshatwar <nikhil.nd at ti.com>
> ---
>  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> index 2cd809eed827..6beccd2a408e 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> @@ -2146,7 +2146,8 @@ static void cdns_mhdp_bridge_hpd_enable(struct
> drm_bridge *bridge)
> 
>  	/* Enable SW event interrupts */
>  	if (mhdp->bridge_attached)
> -		writel(~(u32)CDNS_APB_INT_MASK_SW_EVENT_INT,
> +		writel(readl(mhdp->regs + CDNS_APB_INT_MASK) &
> +		       ~CDNS_APB_INT_MASK_SW_EVENT_INT,
>  		       mhdp->regs + CDNS_APB_INT_MASK);  }
> 
> @@ -2154,7 +2155,9 @@ static void cdns_mhdp_bridge_hpd_disable(struct
> drm_bridge *bridge)  {
>  	struct cdns_mhdp_device *mhdp = bridge_to_mhdp(bridge);
> 
> -	writel(CDNS_APB_INT_MASK_SW_EVENT_INT, mhdp->regs +
> CDNS_APB_INT_MASK);
> +	writel(readl(mhdp->regs + CDNS_APB_INT_MASK) |
> +	       CDNS_APB_INT_MASK_SW_EVENT_INT,
> +	       mhdp->regs + CDNS_APB_INT_MASK);
>  }
> 

Can we do similar change at other places in driver too?
Other than that:
Reviewed-by: Swapnil Jakhade <sjakhade at cadence.com>

Thanks & regards,
Swapnil

>  static const struct drm_bridge_funcs cdns_mhdp_bridge_funcs = {
> --
> 2.17.1