Re: [PATCH] clk: sunxi-ng: a523: Mark MBUS clock as critical
From: Andre Przywara <andre.przywara@arm.com>
Date: 2025-06-12 08:25:57
Also in:
linux-clk, linux-sunxi, lkml
Hi Chen-Yu, thanks for your research on this! On 07/06/2025 14:50, Chen-Yu Tsai wrote:
From: Chen-Yu Tsai <redacted> The MBUS serves as the main data bus for various DMA masters in the system. If its clock is not enabled, the DMA operations will stall, leading to the peripherals stalling or timing out. This has been observed as USB or MMC hosts timing out waiting for transactions when the clock is automatically disabled by the CCF due to it not being used. Mark the clock as critical so that it never gets disabled.
Yes, we do this for all the other SoCs, and I somehow missed that for the A523. I am still scratching my head how this worked for me, though, but the patch is pretty surely correct:
Fixes: 74b0443a0d0a ("clk: sunxi-ng: a523: add system mod clocks")
Signed-off-by: Chen-Yu Tsai <redacted>Reviewed-by: Andre Przywara <andre.przywara@arm.com> Cheers, Andre
quoted hunk ↗ jump to hunk
--- drivers/clk/sunxi-ng/ccu-sun55i-a523.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/drivers/clk/sunxi-ng/ccu-sun55i-a523.c b/drivers/clk/sunxi-ng/ccu-sun55i-a523.c index 9efb9fd24b42..1a9a1cb869e2 100644 --- a/drivers/clk/sunxi-ng/ccu-sun55i-a523.c +++ b/drivers/clk/sunxi-ng/ccu-sun55i-a523.c@@ -385,7 +385,8 @@ static SUNXI_CCU_MP_DATA_WITH_MUX_GATE_FEAT(mbus_clk, "mbus", mbus_parents, 0, 0, /* no P */ 24, 3, /* mux */ BIT(31), /* gate */ - 0, CCU_FEATURE_UPDATE_BIT); + CLK_IS_CRITICAL, + CCU_FEATURE_UPDATE_BIT); static const struct clk_hw *mbus_hws[] = { &mbus_clk.common.hw };