Hello All,
I am seeking recommendations for DRM compatible methods of updating the HW other than frame commit path. When exiting idle/runtime_suspend, the driver votes for a bunch of resources including power/clk/bandwidth as a part of first commit handling. This usually adds a few millisecond delay before processing the frame. The requirement is to find possible ways to reduce this delay by providing an early intimation to the framework to "prepare" the HW by voting for the resources and keep the HW ready to process an imminent frame commit. Especially in performance oriented Automotive world, these delays are very time critical and we are working on ways to mitigate them.
DRM framework converges all the parameters affecting the HW in terms of DRM properties in a single COMMIT call. To address the above issue, we need a parallel channel which should allow the framework to make necessary changes to the HW without violating the master access privileges.
Before resorting to custom downstream ways, I want to check with the community for folks who might have encountered and resolved such issues.
Thanks and Regards,
Jeykumar S
Qualcomm Inc.
On Thu, Feb 20, 2020 at 10:45:57AM -0800, jsanka@codeaurora.org wrote:
Hello All,
I am seeking recommendations for DRM compatible methods of updating the HW other than frame commit path. When exiting idle/runtime_suspend, the driver votes for a bunch of resources including power/clk/bandwidth as a part of first commit handling. This usually adds a few millisecond delay before processing the frame. The requirement is to find possible ways to reduce this delay by providing an early intimation to the framework to "prepare" the HW by voting for the resources and keep the HW ready to process an imminent frame commit. Especially in performance oriented Automotive world, these delays are very time critical and we are working on ways to mitigate them.
DRM framework converges all the parameters affecting the HW in terms of DRM properties in a single COMMIT call. To address the above issue, we need a parallel channel which should allow the framework to make necessary changes to the HW without violating the master access privileges.
Before resorting to custom downstream ways, I want to check with the community for folks who might have encountered and resolved such issues.
Just enable the display, which will grab all the clocks and everything? Once the display is on a commit should be possible on the next frame, at least for well-working drivers. -Daniel
Thanks and Regards,
Jeykumar S
Qualcomm Inc.
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On 2020-02-20 12:14, Daniel Vetter wrote:
On Thu, Feb 20, 2020 at 10:45:57AM -0800, jsanka@codeaurora.org wrote:
Hello All,
I am seeking recommendations for DRM compatible methods of updating the
HW
other than frame commit path. When exiting idle/runtime_suspend, the
driver
votes for a bunch of resources including power/clk/bandwidth as a part
of
first commit handling. This usually adds a few millisecond delay before processing the frame. The requirement is to find possible ways to reduce this delay by providing an early intimation to the framework to
"prepare"
the HW by voting for the resources and keep the HW ready to process an imminent frame commit. Especially in performance oriented Automotive
world,
these delays are very time critical and we are working on ways to
mitigate
them.
DRM framework converges all the parameters affecting the HW in terms of
DRM
properties in a single COMMIT call. To address the above issue, we need
a
parallel channel which should allow the framework to make necessary
changes
to the HW without violating the master access privileges.
Before resorting to custom downstream ways, I want to check with the community for folks who might have encountered and resolved such issues.
Just enable the display, which will grab all the clocks and everything? Once the display is on a commit should be possible on the next frame, at least for well-working drivers. -Daniel
I believe even to turn on the display, DRM will need an explicit commit (probably without any planes/pixel buffers). For cases like smart panels, where we can keep the panel on(panel internal RAM refresh) and power collapse the display HW, resuming back with an explicit commit will push a black (or default color programmed in the HW) frame causing a glitch.
Thanks and Regards, Jeykumar S.
Thanks and Regards,
Jeykumar S
Qualcomm Inc.
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On Thu, Feb 20, 2020 at 01:24:00PM -0800, jsanka@codeaurora.org wrote:
On 2020-02-20 12:14, Daniel Vetter wrote:
On Thu, Feb 20, 2020 at 10:45:57AM -0800, jsanka@codeaurora.org wrote:
Hello All,
I am seeking recommendations for DRM compatible methods of updating the
HW
other than frame commit path. When exiting idle/runtime_suspend, the
driver
votes for a bunch of resources including power/clk/bandwidth as a part
of
first commit handling. This usually adds a few millisecond delay before processing the frame. The requirement is to find possible ways to reduce this delay by providing an early intimation to the framework to
"prepare"
the HW by voting for the resources and keep the HW ready to process an imminent frame commit. Especially in performance oriented Automotive
world,
these delays are very time critical and we are working on ways to
mitigate
them.
DRM framework converges all the parameters affecting the HW in terms of
DRM
properties in a single COMMIT call. To address the above issue, we need
a
parallel channel which should allow the framework to make necessary
changes
to the HW without violating the master access privileges.
Before resorting to custom downstream ways, I want to check with the community for folks who might have encountered and resolved such issues.
Just enable the display, which will grab all the clocks and everything? Once the display is on a commit should be possible on the next frame, at least for well-working drivers. -Daniel
I believe even to turn on the display, DRM will need an explicit commit (probably without any planes/pixel buffers). For cases like smart panels, where we can keep the panel on(panel internal RAM refresh) and power collapse the display HW, resuming back with an explicit commit will push a black (or default color programmed in the HW) frame causing a glitch.
Uh, you might want to look into the self-refresh helpers, which do this without black frames and stuff.
But yeah if there's really a gap here (and not just you folks creatively abusing atomic kms in ways that it was not meant to be used) then we can add a property that forbids power optimization and guarantee that you can do the next screen update immediately. And then we can merge that with all the usual requirements (driver implementation that works, open source userspace, igt testcase, the full deal).
But it still feels like you're trying to do something automatically that's not meant to work like this.
Cheers, Daniel
Thanks and Regards, Jeykumar S.
Thanks and Regards,
Jeykumar S
Qualcomm Inc.
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
On 2020-02-21 09:20, Daniel Vetter wrote:
On Thu, Feb 20, 2020 at 01:24:00PM -0800, jsanka@codeaurora.org wrote:
On 2020-02-20 12:14, Daniel Vetter wrote:
On Thu, Feb 20, 2020 at 10:45:57AM -0800, jsanka@codeaurora.org wrote:
Hello All,
I am seeking recommendations for DRM compatible methods of updating the
HW
other than frame commit path. When exiting idle/runtime_suspend, the
driver
votes for a bunch of resources including power/clk/bandwidth as a
part
of
first commit handling. This usually adds a few millisecond delay before processing the frame. The requirement is to find possible ways to reduce this delay by providing an early intimation to the framework to
"prepare"
the HW by voting for the resources and keep the HW ready to process
an
imminent frame commit. Especially in performance oriented Automotive
world,
these delays are very time critical and we are working on ways to
mitigate
them.
DRM framework converges all the parameters affecting the HW in terms of
DRM
properties in a single COMMIT call. To address the above issue, we need
a
parallel channel which should allow the framework to make necessary
changes
to the HW without violating the master access privileges.
Before resorting to custom downstream ways, I want to check with the community for folks who might have encountered and resolved such issues.
Just enable the display, which will grab all the clocks and
everything?
Once the display is on a commit should be possible on the next frame,
at
least for well-working drivers. -Daniel
I believe even to turn on the display, DRM will need an explicit commit (probably without any planes/pixel buffers). For cases like smart
panels,
where we can keep the panel on(panel internal RAM refresh) and power collapse the display HW, resuming back with an explicit commit will push
a
black (or default color programmed in the HW) frame causing a glitch.
Uh, you might want to look into the self-refresh helpers, which do this without black frames and stuff.
I believe you are referring to Sean's PSR changes: https://patchwork.freedesktop.org/series/57366/ Will take a look.
Thanks and Regards, Jeykumar S.
But yeah if there's really a gap here (and not just you folks creatively abusing atomic kms in ways that it was not meant to be used) then we can add a property that forbids power optimization and guarantee that you can do the next screen update immediately. And then we can merge that with all the usual requirements (driver implementation that works, open source userspace, igt testcase, the full deal).
But it still feels like you're trying to do something automatically that's not meant to work like this.
Cheers, Daniel
Thanks and Regards, Jeykumar S.
Thanks and Regards,
Jeykumar S
Qualcomm Inc.
dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
jsanka＠codeaurora.org