On some pinephones the video output sometimes freezes (flips between two
frames) [1]. It seems to be that the reason for this behaviour is that
PLL-MIPI is outside its limits, and the GPU is not running at a fixed
rate.
In this patch series I propose the following changes:
1. sunxi-ng: Adhere to the following constraints given in the
Allwinner A64 Manual regarding PLL-MIPI:
* M/N <= 3
* (PLL_VIDEO0)/M >= 24MHz
* 500MHz <= clockrate <= 1400MHz
2. Remove two operating points from the A64 DTS OPPs, so that the GPU
runs at a fixed rate of 432 MHz.
Note, that when pinning the GPU to 432 MHz the issue [1] completely
disappears for me. I've searched the BSP and could not find any
indication that supports the idea of having the three OPPs. The only
frequency I found in the BPSs for A64 is 432 MHz, which has also proven
stable for me.
I very much appreciate your feedback!
[1] https://gitlab.com/postmarketOS/pmaports/-/issues/805
Signed-off-by: Frank Oltmanns <frank@xxxxxxxxxxxx>
---
Changes in v4:
- sunxi-ng: common: Address review comments.
- Link to v3: https://lore.kernel.org/r/20240304-pinephone-pll-fixes-v3-0-94ab828f269a@xxxxxxxxxxxx
Changes in v3:
- dts: Pin GPU to 432 MHz.
- nkm and a64: Move minimum and maximum rate handling to the common part
of the sunxi-ng driver.
- Removed st7703 patch from series.
- Link to v2: https://lore.kernel.org/r/20240205-pinephone-pll-fixes-v2-0-96a46a2d8c9b@xxxxxxxxxxxx
Changes in v2:
- dts: Increase minimum GPU frequency to 192 MHz.
- nkm and a64: Add minimum and maximum rate for PLL-MIPI.
- nkm: Use the same approach for skipping invalid rates in
ccu_nkm_find_best() as in ccu_nkm_find_best_with_parent_adj().
- nkm: Improve names for ratio struct members and hence get rid of
describing comments.
- nkm and a64: Correct description in the commit messages: M/N <= 3
- Remove patches for nm as they were not needed.
- st7703: Rework the commit message to cover more background for the
change.
- Link to v1: https://lore.kernel.org/r/20231218-pinephone-pll-fixes-v1-0-e238b6ed6dc1@xxxxxxxxxxxx
---
Frank Oltmanns (5):
clk: sunxi-ng: common: Support minimum and maximum rate
clk: sunxi-ng: a64: Set minimum and maximum rate for PLL-MIPI
clk: sunxi-ng: nkm: Support constraints on m/n ratio and parent rate
clk: sunxi-ng: a64: Add constraints on PLL-MIPI's n/m ratio and parent rate
arm64: dts: allwinner: a64: Run GPU at 432 MHz
arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 8 --------
drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 14 +++++++++-----
drivers/clk/sunxi-ng/ccu_common.c | 19 +++++++++++++++++++
drivers/clk/sunxi-ng/ccu_common.h | 3 +++
drivers/clk/sunxi-ng/ccu_nkm.c | 21 +++++++++++++++++++++
drivers/clk/sunxi-ng/ccu_nkm.h | 2 ++
6 files changed, 54 insertions(+), 13 deletions(-)
---
base-commit: dcb6c8ee6acc6c347caec1e73fb900c0f4ff9806
change-id: 20231218-pinephone-pll-fixes-0ccdfde273e4
Best regards,
--
Frank Oltmanns <frank@xxxxxxxxxxxx>
