linux-kernel - [PATCH v4 2/2] clk: samsung: gs101: don't mark non-essential (UART) clocks critical

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Message-Id: <20240712-gs101-non-essential-clocks-2-v4-2-310aee0de46e@linaro.org>
Date: Fri, 12 Jul 2024 18:09:44 +0100
From: André Draszik <andre.draszik@...aro.org>
To: Peter Griffin <peter.griffin@...aro.org>, 
 Krzysztof Kozlowski <krzk@...nel.org>, 
 Sylwester Nawrocki <s.nawrocki@...sung.com>, 
 Chanwoo Choi <cw00.choi@...sung.com>, Alim Akhtar <alim.akhtar@...sung.com>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Tudor Ambarus <tudor.ambarus@...aro.org>, 
 Sam Protsenko <semen.protsenko@...aro.org>
Cc: Tudor Ambarus <tudor.ambarus@...aro.org>, 
 Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org, 
 linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, 
 André Draszik <andre.draszik@...aro.org>
Subject: [PATCH v4 2/2] clk: samsung: gs101: don't mark non-essential
 (UART) clocks critical

The peric0_top1_ipclk_0 and peric0_top1_pclk_0 are the clocks going to
peric0/uart_usi, with pclk being the bus clock. Without pclk running,
any bus access will hang.
Unfortunately, in commit d97b6c902a40 ("arm64: dts: exynos: gs101:
update USI UART to use peric0 clocks") the gs101 DT ended up specifying
an incorrect pclk in the respective node and instead the two clocks
here were marked as critical.

Since then, the DT has been updated to use the correct clock in
commit 21e4e8807bfc ("arm64: dts: exynos: gs101: use correct clocks for
usi_uart") and the driver here should be corrected and the work-around
removed.

Link: https://lore.kernel.org/all/d45de3b2bb6b48653842cf1f74e58889ed6783ae.camel@linaro.org/ [1]
Fixes: 893f133a040b ("clk: samsung: gs101: add support for cmu_peric0")
Signed-off-by: André Draszik <andre.draszik@...aro.org>
Reviewed-by: Tudor Ambarus <tudor.ambarus@...aro.org>
Reviewed-by: Sam Protsenko <semen.protsenko@...aro.org>

---
v4:
- the earlycon issue described in the commit message in previous
  versions of this patch is gone with "clk: samsung: gs101: allow
  earlycon to work unconditionally", so no need to mention anything

v3:
- add git commit SHA1s (Krzysztof)
- add link to wordier description of earlycon issue

v2:
- commit message typo fixed
- collect Reviewed-by: tags
---
 drivers/clk/samsung/clk-gs101.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/samsung/clk-gs101.c b/drivers/clk/samsung/clk-gs101.c
index 429690757923..a6fc4d7e47fd 100644
--- a/drivers/clk/samsung/clk-gs101.c
+++ b/drivers/clk/samsung/clk-gs101.c
@@ -3951,20 +3951,18 @@ static const struct samsung_gate_clock peric0_gate_clks[] __initconst = {
 	     "gout_peric0_peric0_top0_pclk_9", "mout_peric0_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP0_IPCLKPORT_PCLK_9,
 	     21, 0, 0),
-	/* Disabling this clock makes the system hang. Mark the clock as critical. */
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP1_IPCLK_0,
 	     "gout_peric0_peric0_top1_ipclk_0", "dout_peric0_usi0_uart",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP1_IPCLKPORT_IPCLK_0,
-	     21, CLK_IS_CRITICAL, 0),
+	     21, 0, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP1_IPCLK_2,
 	     "gout_peric0_peric0_top1_ipclk_2", "dout_peric0_usi14_usi",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP1_IPCLKPORT_IPCLK_2,
 	     21, CLK_SET_RATE_PARENT, 0),
-	/* Disabling this clock makes the system hang. Mark the clock as critical. */
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP1_PCLK_0,
 	     "gout_peric0_peric0_top1_pclk_0", "mout_peric0_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP1_IPCLKPORT_PCLK_0,
-	     21, CLK_IS_CRITICAL, 0),
+	     21, 0, 0),
 	GATE(CLK_GOUT_PERIC0_PERIC0_TOP1_PCLK_2,
 	     "gout_peric0_peric0_top1_pclk_2", "mout_peric0_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_PERIC0_UID_PERIC0_TOP1_IPCLKPORT_PCLK_2,

-- 
2.45.2.993.g49e7a77208-goog