Re: [PATCH v3 3/3] clk: qcom: Add display clock controller driver for SDM845

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 7/9/2018 1:07 PM, Stephen Boyd wrote:
Quoting Taniya Das (2018-07-09 00:07:21)


On 7/9/2018 11:46 AM, Stephen Boyd wrote:

   > Why is the nocache flag needed? Applies to all clks in this file.
   >

This flag is required for all RCGs whose PLLs are controlled outside the
clock controller. The display code would require the recalculated rate
always.

Right. Why is the PLL controlled outside of the clock controller? The
rate should propagate upward to the PLL from here, so who's going
outside of that?

The DSI0/1 PLL are not part of the display clock controller, but in the
display subsystem which are managed by the DRM drivers. When DRM drivers
query for the rate clock driver should always return the non cached rates.

Why? Is the DSI PLL changing rate all the time, randomly, without going
through the clk APIs to do so?


Hmm, I am afraid I do not have an answer for this, but this was the requirement to always return the non cached rates from the clock driver.

--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation.

--
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux