linux-kernel - Re: [PATCH 1/2] media: ov5675: Derive delay cycles from the clock rate reported

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Message-ID: <2e350b8b-a816-42db-b5eb-0dd257df8a58@cherry.de>
Date: Thu, 11 Jul 2024 12:32:22 +0200
From: Quentin Schulz <quentin.schulz@...rry.de>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
 Sakari Ailus <sakari.ailus@...ux.intel.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Quentin Schulz <quentin.schulz@...obroma-systems.com>,
 Jacopo Mondi <jacopo@...ndi.org>
Cc: Johan Hovold <johan@...nel.org>,
 Kieran Bingham <kieran.bingham@...asonboard.com>,
 linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] media: ov5675: Derive delay cycles from the clock
 rate reported

Hi Bryan,

On 7/11/24 12:20 PM, Bryan O'Donoghue wrote:
> The ov5675 driver expresses its reset delays in terms of XVCLK cycles as
> per the ov5675 specification. XVCLK can be anything in the range of 6 MHz
> to 24 MHz inclusive.
> 
> Upstream we use 19.2 MHz however, since the delays are calculated in terms
> of clock cycles as opposed to fixed intervals it makes sense to facilitate
> any potential clock we might support.
> 
> Do so by reading the XVCLK rate and using the returned rate instead of
> operating from a static definition.
> 

We're actually running this sensor at **almost** 19.2MHz but are having 
intermittent issues, so this could probably help us too. In the end (for 
my employer), we should just add support for 24MHz as that's a frequency 
our products support but I'm lacking time right now. One day hopefully.

> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>

The change isn't really useful for upstream yet but makes sense to me, so:

Reviewed-by: Quentin Schulz <quentin.schulz@...rry.de>

Thanks!
Quentin