From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v7] clk: bcm2835: Add support for programming the audio domain clocks To: Eric Anholt References: <1444354644-31997-1-git-send-email-eric@anholt.net> Cc: linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Lee Jones , Stephen Boyd , Mike Turquette From: Stephen Warren Message-ID: <561720F9.1080206@wwwdotorg.org> Date: Thu, 8 Oct 2015 20:05:45 -0600 MIME-Version: 1.0 In-Reply-To: <1444354644-31997-1-git-send-email-eric@anholt.net> Content-Type: text/plain; charset=windows-1252 List-ID: On 10/08/2015 07:37 PM, Eric Anholt wrote: > This adds support for enabling, disabling, and setting the rate of the > audio domain clocks. It will be necessary for setting the pixel clock > for HDMI in the VC4 driver and let us write a cpufreq driver. It will > also improve compatibility with user changes to the firmware's > config.txt, since our previous fixed clocks are unaware of it. > > The firmware also has support for configuring the clocks through the > mailbox channel, but the pixel clock setup by the firmware doesn't > work, and it's Raspberry Pi specific anyway. The only conflicts we > should have with the firmware would be if we made firmware calls that > result in clock management (like opening firmware V3D or ISP access, > which we don't support in upstream), or on hardware over-thermal or > under-voltage (when the firmware would rewrite PLLB to take the ARM > out of overclock). If that happens, our cached .recalc_rate() results > would be incorrect, but that's no worse than our current state where > we used fixed clocks. > > The existing fixed clocks in the code are left in place to provide > backwards compatibility with old device tree files. Acked-by: Stephen Warren