From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Boyd Subject: Re: [PATCH 2/2] drm/msm: Don't provide 'is_enabled' PLL clk_ops Date: Tue, 25 Oct 2016 13:28:32 -0700 Message-ID: <20161025202832.GY26139@codeaurora.org> References: <1477378080-16087-1-git-send-email-architt@codeaurora.org> <1477378080-16087-3-git-send-email-architt@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1477378080-16087-3-git-send-email-architt@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org To: Archit Taneja Cc: robdclark@gmail.com, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org On 10/25, Archit Taneja wrote: > The DSI/HDMI PLLs in MSM require resources like interface clocks, power > domains to be enabled before we can access their registers. > > The clock framework doesn't have a mechanism at the moment where we can > tie such resources to a clock, so we make sure that the KMS driver enables > these resources whenever a PLL is expected to be in use. > > One place where we can't ensure the resource dependencies are met is when > the clock framework tries to disable unused clocks. The KMS driver doesn't > know when the clock framework calls the is_enabled clk_op, and hence can't > enable interface clocks/power domains beforehand. > > We remove the is_enabled clk_ops from the PLL clocks for now since they > aren't mandatory. This needs to be revisited, since bootloaders can enable > display, the enable count maintained by clock framework wouldn't work in > such cases. > > Cc: Stephen Boyd > Signed-off-by: Archit Taneja > --- Why not use the CLK_IGNORE_UNUSED flag for now? That does essentially the same thing without requiring us to reintroduce this code later on. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project