From: Taniya Das <tdas@xxxxxxxxxxxxxx> [ Upstream commit 9c3df2b1993da9ab1110702d7b2815d5cd8c02f3 ] The display gpll0 branch clock inside GCC needs to always be enabled. Otherwise the AHB clk (disp_cc_mdss_ahb_clk_src) for the display clk controller (dispcc) will stop clocking while sourcing from gpll0 when this branch inside GCC is turned off during unused clk disabling. We can never turn this branch off because the AHB clk for the display subsystem is needed to read/write any registers inside the display subsystem including clk related ones. This makes this branch a really easy way to turn off AHB access to the display subsystem and cause all sorts of mayhem. Let's just make the clk ops keep the clk enabled forever and ignore any attempts to disable this clk so that dispcc accesses keep working. Signed-off-by: Taniya Das <tdas@xxxxxxxxxxxxxx> Reported-by: Evan Green <evgreen@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/1594796050-14511-1-git-send-email-tdas@xxxxxxxxxxxxxx Fixes: 17269568f726 ("clk: qcom: Add Global Clock controller (GCC) driver for SC7180") Fixes: 06391eddb60a ("clk: qcom: Add Global Clock controller (GCC) driver for SDM845") [sboyd@xxxxxxxxxx: Fill out commit text more] Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/clk/qcom/gcc-sc7180.c | 2 +- drivers/clk/qcom/gcc-sdm845.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/clk/qcom/gcc-sc7180.c b/drivers/clk/qcom/gcc-sc7180.c index 73380525cb091..b3704b685cca3 100644 --- a/drivers/clk/qcom/gcc-sc7180.c +++ b/drivers/clk/qcom/gcc-sc7180.c @@ -1041,7 +1041,7 @@ static struct clk_branch gcc_disp_gpll0_clk_src = { .hw = &gpll0.clkr.hw, }, .num_parents = 1, - .ops = &clk_branch2_ops, + .ops = &clk_branch2_aon_ops, }, }, }; diff --git a/drivers/clk/qcom/gcc-sdm845.c b/drivers/clk/qcom/gcc-sdm845.c index f6ce888098be9..90f7febaf5288 100644 --- a/drivers/clk/qcom/gcc-sdm845.c +++ b/drivers/clk/qcom/gcc-sdm845.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * Copyright (c) 2018, The Linux Foundation. All rights reserved. + * Copyright (c) 2018, 2020, The Linux Foundation. All rights reserved. */ #include <linux/kernel.h> @@ -1344,7 +1344,7 @@ static struct clk_branch gcc_disp_gpll0_clk_src = { "gpll0", }, .num_parents = 1, - .ops = &clk_branch2_ops, + .ops = &clk_branch2_aon_ops, }, }, }; -- 2.25.1
