[linux-sunxi] Re: [PATCH 4/4] simplefb: add clock handling code
From: Michal Suchanek <hidden>
Date: 2014-08-27 20:57:29
Also in:
linux-fbdev
Hello, On 27 August 2014 17:42, Maxime Ripard [off-list ref] wrote:
On Wed, Aug 27, 2014 at 11:52:48AM +0200, Thierry Reding wrote:quoted
On Wed, Aug 27, 2014 at 10:45:26AM +0200, Maxime Ripard wrote:quoted
On Wed, Aug 27, 2014 at 08:54:41AM +0200, Thierry Reding wrote:quoted
On Tue, Aug 26, 2014 at 11:02:48PM +0200, Maxime Ripard wrote:quoted
On Tue, Aug 26, 2014 at 04:35:51PM +0200, Thierry Reding wrote:[...]quoted
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Mike Turquette repeatedly said that he was against such a DT property: https://lkml.org/lkml/2014/5/12/693Mike says in that email that he's opposing the addition of a property for clocks that is the equivalent of regulator-always-on. That's not what this is about. If at all it'd be a property to mark a clock that should not be disabled by default because it's essential.It's just semantic. How is "a clock that should not be disabled by default because it's essential" not a clock that stays always on?Because a clock that should not be disabled by default can be turned off when appropriate. A clock that is always on can't be turned off.If a clock is essential, then it should never be disabled. Or we don't share the same meaning of essential.Essential for the particular use-case.So, how would the clock driver would know about which use case we're in? How would it know about which display engine is currently running? How would it know about which video output is being set? Currently, we have two separate display engines, which can each output either to 4 different outputs (HDMI, RGB/LVDS, 2 DSI). Each and every one of these combinations would require different clocks. What clocks will we put in the driver? All of them?
since simplefb cannot be extended how about adding, say, dtfb which claims the resources from dt and then instantiates a simplefb once the resources are claimed? That is have a dtfb which has the clocks assigned and has simplefb as child dt node. Thanks Michal