linux-kernel - Re: [PATCH 09/10] drm/imx: Add i.MX8qxp Display Controller KMS

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Message-ID: <3b91320f-730e-46e4-9c96-8c348bf9a2a2@nxp.com>
Date: Mon, 8 Jul 2024 14:21:06 +0800
From: Liu Ying <victor.liu@....com>
To: Markus Elfring <Markus.Elfring@....de>, dri-devel@...ts.freedesktop.org,
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 kernel@...gutronix.de, devicetree@...r.kernel.org
Cc: LKML <linux-kernel@...r.kernel.org>, Conor Dooley <conor+dt@...nel.org>,
 Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>,
 Fabio Estevam <festevam@...il.com>, Krzysztof Kozlowski
 <krzk+dt@...nel.org>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>,
 Rob Herring <robh@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Shawn Guo <shawnguo@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH 09/10] drm/imx: Add i.MX8qxp Display Controller KMS

On 07/08/2024, Markus Elfring wrote:
> …
>> registers of the display controller is accessed without command sequencer
> …
> 
> Wording suggestion:
>   The registers of …                  are …

Will do.

> 
> 
> …
>> +++ b/drivers/gpu/drm/imx/dc/dc-crtc.c
>> @@ -0,0 +1,578 @@
> …
>> +static irqreturn_t
>> +dc_crtc_dec_framecomplete_irq_handler(int irq, void *dev_id)
>> +{
> …
>> +	spin_lock_irqsave(&crtc->dev->event_lock, flags);
>> +	if (dc_crtc->event) {
> …
>> +	}
>> +	spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
>> +
>> +	return IRQ_HANDLED;
>> +}
> …
> 
> Under which circumstances would you become interested to apply a statement
> like “guard(spinlock_irqsave)(&crtc->dev->event_lock);”?

I just follow the kerneldoc of drm_crtc_send_vblank_event() to
hold event lock like many other drivers do.

https://elixir.bootlin.com/linux/v6.10-rc6/source/drivers/gpu/drm/drm_vblank.c#L1120

> https://elixir.bootlin.com/linux/v6.10-rc6/source/include/linux/spinlock.h#L574
> 
> Regards,
> Markus

-- 
Regards,
Liu Ying