Enabling UFSHCD_CAP_HIBERN8_WITH_CLK_GATING in the UFS driver means
all UFS clocks are gated/ungated, which leads to the UFS IP getting
into a bad state and being completely non functional.

Downstream these clocks are all left in Automatic Clock Gate (ACG)
mode, and are not exposed to the UFS driver in DT. Enabling ACG is
ultimately what we need to do in the upstream Samsung clock driver
as well.

However until ACG is enabled upstream, we mark these clocks as
critical to avoid them being disabled. This then allow us to enable
UFSHCD_CAP_HIBERN8_WITH_CLK_GATING and have UFS hibern8.

Whilst this may seem at first glance a strange thing to do, the clocks
between UFS host and UFS device are still gated after this change, and
enabling UFS hibern8 leads to substantially cooler device when running
the upstream kernel on a Pixel 6 phone. This change only effects the
clocks from the CMU to the UFS IP.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
 drivers/clk/samsung/clk-gs101.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/samsung/clk-gs101.c b/drivers/clk/samsung/clk-gs101.c
index 85098c61c15e..86b39edba122 100644
--- a/drivers/clk/samsung/clk-gs101.c
+++ b/drivers/clk/samsung/clk-gs101.c
@@ -2775,11 +2775,11 @@ static const struct samsung_gate_clock hsi2_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_HSI2_QE_UFS_EMBD_HSI2_ACLK,
 	     "gout_hsi2_qe_ufs_embd_hsi2_aclk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_QE_UFS_EMBD_HSI2_IPCLKPORT_ACLK,
-	     21, 0, 0),
+	     21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_HSI2_QE_UFS_EMBD_HSI2_PCLK,
 	     "gout_hsi2_qe_ufs_embd_hsi2_pclk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_QE_UFS_EMBD_HSI2_IPCLKPORT_PCLK,
-	     21, 0, 0),
+	     21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_HSI2_CLK_HSI2_BUS_CLK,
 	     "gout_hsi2_clk_hsi2_bus_clk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_RSTNSYNC_CLK_HSI2_BUS_IPCLKPORT_CLK,
@@ -2806,7 +2806,7 @@ static const struct samsung_gate_clock hsi2_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_HSI2_SYSREG_HSI2_PCLK,
 	     "gout_hsi2_sysreg_hsi2_pclk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_SYSREG_HSI2_IPCLKPORT_PCLK,
-	     21, 0, 0),
+	     21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_HSI2_UASC_PCIE_GEN4A_DBI_1_ACLK,
 	     "gout_hsi2_uasc_pcie_gen4a_dbi_1_aclk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_UASC_PCIE_GEN4A_DBI_1_IPCLKPORT_ACLK,
@@ -2842,7 +2842,7 @@ static const struct samsung_gate_clock hsi2_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_HSI2_UFS_EMBD_I_ACLK,
 	     "gout_hsi2_ufs_embd_i_aclk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_UFS_EMBD_IPCLKPORT_I_ACLK,
-	     21, 0, 0),
+	     21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_HSI2_UFS_EMBD_I_CLK_UNIPRO,
 	     "gout_hsi2_ufs_embd_i_clk_unipro", "mout_hsi2_ufs_embd_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_UFS_EMBD_IPCLKPORT_I_CLK_UNIPRO,
@@ -2850,7 +2850,7 @@ static const struct samsung_gate_clock hsi2_gate_clks[] __initconst = {
 	GATE(CLK_GOUT_HSI2_UFS_EMBD_I_FMP_CLK,
 	     "gout_hsi2_ufs_embd_i_fmp_clk", "mout_hsi2_bus_user",
 	     CLK_CON_GAT_GOUT_BLK_HSI2_UID_UFS_EMBD_IPCLKPORT_I_FMP_CLK,
-	     21, 0, 0),
+	     21, CLK_IS_CRITICAL, 0),
 	/* TODO: should have a driver for this */
 	GATE(CLK_GOUT_HSI2_XIU_D_HSI2_ACLK,
 	     "gout_hsi2_xiu_d_hsi2_aclk", "mout_hsi2_bus_user",
-- 
2.47.0.rc1.288.g06298d1525-goog

On Fri, 18 Oct 2024 14:02:15 +0100, Peter Griffin wrote:
> Enabling UFSHCD_CAP_HIBERN8_WITH_CLK_GATING in the UFS driver means
> all UFS clocks are gated/ungated, which leads to the UFS IP getting
> into a bad state and being completely non functional.
> 
> Downstream these clocks are all left in Automatic Clock Gate (ACG)
> mode, and are not exposed to the UFS driver in DT. Enabling ACG is
> ultimately what we need to do in the upstream Samsung clock driver
> as well.
> 
> [...]

Applied, thanks!

[1/1] clk: samsung: gs101: make all ufs related clocks critical
      https://git.kernel.org/krzk/linux/c/6aff357efc2bb060e5b400774becfd3d37644b44

Best regards,
-- 
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>