linux-kernel - Re: [PATCH 0/3] refactor some ldb related clocks

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Date:	Tue, 20 Aug 2013 11:43:43 +0200
From:	Philipp Zabel <p.zabel@...gutronix.de>
To:	Liu Ying <Ying.Liu@...escale.com>
Cc:	kernel@...gutronix.de, gregkh@...uxfoundation.org,
	shawn.guo@...aro.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 0/3] refactor some ldb related clocks

Am Dienstag, den 20.08.2013, 16:38 +0800 schrieb Liu Ying:
> The ldb_di[0/1]_ipu_div clock dividers in the CSCMR2 register
> of i.MX53, i.MX6Q and i.MX6DL SoCs can be configured to a 1/3.5
> drivider or a 1/7 divider. The common clock framework cannot
> deal with the two dividers directly even with the divider table
> which only supports integral dividers. So, the idea is to take
> the 1/3.5 and 1/7 dividers as separate fixed factor dividers and
> introduce a new multiplexer clock to be derived from the them.
> Then, the ldb display clock trees can be setup correctly.
> This series contains the necessary clock driver changes, dts code
> changes and imx-drm/ldb driver changes to fullfill the task.

I don't see how this improves the situation. Does this solve any real
problem?

While I admit to having introduced the combination of 1/3.5 fixed
divider and configurable 1/1,1/2 divder clocks to describe this
fractional divider for the reasons you state, I think the correct
solution would be to improve the table divider to support fractional
values and get rid of the virtual ldb_di<n>_div_3_5 clocks, not
introduce more virtual clocks.

regards
Philipp

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