linux-kernel - Re: [PATCH 04/10] drm/tidss: Move reset to the end of dispc

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Message-ID: <71056358-f91e-4a88-a979-33bfe157289a@ideasonboard.com>
Date:   Thu, 2 Nov 2023 08:40:10 +0200
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Aradhya Bhatia <a-bhatia1@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jyri Sarha <jyri.sarha@....fi>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/10] drm/tidss: Move reset to the end of dispc_init()

On 01/11/2023 15:57, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Wed, Nov 01, 2023 at 11:17:41AM +0200, Tomi Valkeinen wrote:
>> We do a DSS reset in the middle of the dispc_init(). While that happens
>> to work now, we should really make sure that e..g the fclk, which is
>> acquired only later in the function, is enabled when doing a reset. This
>> will be handled in a later patch, but for now, let's move the
>> dispc_softreset() call to the end of dispc_init(), which is a sensible
>> place for it anyway.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> 
> But do I understand correctly that the device isn't powered up at this
> point ? That seems problematic.

Indeed. It's fixed later in this series.

> I'm also not sure why we need to reset the device at probe time.

That's the usual place to do a reset, to make sure the HW is in a known 
state, is it not? Where would you place it?

  Tomi