[v2,for-4.9,12/32] clk: bcm2835: Don't rate change PLLs on behalf of DSI PLL dividers.

Message ID 1491388344-13521-13-git-send-email-amit.pundir@linaro.org
State New
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Series
  • Stable commits picked up from lede project
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Commit Message

Amit Pundir April 5, 2017, 10:32 a.m.
From: Eric Anholt <eric@anholt.net>


Our core PLLs are intended to be configured once and left alone.  With
the SET_RATE_PARENT, asking to set the PLLD_DSI1 clock rate would
change PLLD just to get closer to the requested DSI clock, thus
changing PLLD_PER, the UART and ethernet PHY clock rates downstream of
it, and breaking ethernet.

We *do* want PLLH to change so that PLLH_AUX can be exactly the value
we want, though.  Thus, we need to have a per-divider policy of
whether to pass rate changes up.

Signed-off-by: Eric Anholt <eric@anholt.net>

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

(cherry picked from commit 55486091bd1e1c5ed28c43c0d6b3392468a9adb5)
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

---
 drivers/clk/bcm/clk-bcm2835.c | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

-- 
2.7.4

Comments

Eric Anholt April 6, 2017, 4:53 p.m. | #1
Amit Pundir <amit.pundir@linaro.org> writes:

> From: Eric Anholt <eric@anholt.net>

>

> Our core PLLs are intended to be configured once and left alone.  With

> the SET_RATE_PARENT, asking to set the PLLD_DSI1 clock rate would

> change PLLD just to get closer to the requested DSI clock, thus

> changing PLLD_PER, the UART and ethernet PHY clock rates downstream of

> it, and breaking ethernet.

>

> We *do* want PLLH to change so that PLLH_AUX can be exactly the value

> we want, though.  Thus, we need to have a per-divider policy of

> whether to pass rate changes up.


I don't have the full series so I'm not sure why these 3 are being sent
to stable, but they don't seem like stable candidates to me.

Patch

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 0d14409..3d0848d 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -428,6 +428,7 @@  struct bcm2835_pll_divider_data {
 	u32 load_mask;
 	u32 hold_mask;
 	u32 fixed_divider;
+	u32 flags;
 };
 
 struct bcm2835_clock_data {
@@ -1252,7 +1253,7 @@  bcm2835_register_pll_divider(struct bcm2835_cprman *cprman,
 	init.num_parents = 1;
 	init.name = divider_name;
 	init.ops = &bcm2835_pll_divider_clk_ops;
-	init.flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED;
+	init.flags = data->flags | CLK_IGNORE_UNUSED;
 
 	divider = devm_kzalloc(cprman->dev, sizeof(*divider), GFP_KERNEL);
 	if (!divider)
@@ -1466,7 +1467,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLA_CORE,
 		.load_mask = CM_PLLA_LOADCORE,
 		.hold_mask = CM_PLLA_HOLDCORE,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLA_PER]	= REGISTER_PLL_DIV(
 		.name = "plla_per",
 		.source_pll = "plla",
@@ -1474,7 +1476,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLA_PER,
 		.load_mask = CM_PLLA_LOADPER,
 		.hold_mask = CM_PLLA_HOLDPER,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLA_DSI0]	= REGISTER_PLL_DIV(
 		.name = "plla_dsi0",
 		.source_pll = "plla",
@@ -1490,7 +1493,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLA_CCP2,
 		.load_mask = CM_PLLA_LOADCCP2,
 		.hold_mask = CM_PLLA_HOLDCCP2,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 
 	/* PLLB is used for the ARM's clock. */
 	[BCM2835_PLLB]		= REGISTER_PLL(
@@ -1514,7 +1518,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLB_ARM,
 		.load_mask = CM_PLLB_LOADARM,
 		.hold_mask = CM_PLLB_HOLDARM,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 
 	/*
 	 * PLLC is the core PLL, used to drive the core VPU clock.
@@ -1543,7 +1548,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLC_CORE0,
 		.load_mask = CM_PLLC_LOADCORE0,
 		.hold_mask = CM_PLLC_HOLDCORE0,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLC_CORE1]	= REGISTER_PLL_DIV(
 		.name = "pllc_core1",
 		.source_pll = "pllc",
@@ -1551,7 +1557,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLC_CORE1,
 		.load_mask = CM_PLLC_LOADCORE1,
 		.hold_mask = CM_PLLC_HOLDCORE1,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLC_CORE2]	= REGISTER_PLL_DIV(
 		.name = "pllc_core2",
 		.source_pll = "pllc",
@@ -1559,7 +1566,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLC_CORE2,
 		.load_mask = CM_PLLC_LOADCORE2,
 		.hold_mask = CM_PLLC_HOLDCORE2,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLC_PER]	= REGISTER_PLL_DIV(
 		.name = "pllc_per",
 		.source_pll = "pllc",
@@ -1567,7 +1575,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLC_PER,
 		.load_mask = CM_PLLC_LOADPER,
 		.hold_mask = CM_PLLC_HOLDPER,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 
 	/*
 	 * PLLD is the display PLL, used to drive DSI display panels.
@@ -1596,7 +1605,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLD_CORE,
 		.load_mask = CM_PLLD_LOADCORE,
 		.hold_mask = CM_PLLD_HOLDCORE,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLD_PER]	= REGISTER_PLL_DIV(
 		.name = "plld_per",
 		.source_pll = "plld",
@@ -1604,7 +1614,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLD_PER,
 		.load_mask = CM_PLLD_LOADPER,
 		.hold_mask = CM_PLLD_HOLDPER,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLD_DSI0]	= REGISTER_PLL_DIV(
 		.name = "plld_dsi0",
 		.source_pll = "plld",
@@ -1649,7 +1660,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLH_RCAL,
 		.load_mask = CM_PLLH_LOADRCAL,
 		.hold_mask = 0,
-		.fixed_divider = 10),
+		.fixed_divider = 10,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLH_AUX]	= REGISTER_PLL_DIV(
 		.name = "pllh_aux",
 		.source_pll = "pllh",
@@ -1657,7 +1669,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLH_AUX,
 		.load_mask = CM_PLLH_LOADAUX,
 		.hold_mask = 0,
-		.fixed_divider = 1),
+		.fixed_divider = 1,
+		.flags = CLK_SET_RATE_PARENT),
 	[BCM2835_PLLH_PIX]	= REGISTER_PLL_DIV(
 		.name = "pllh_pix",
 		.source_pll = "pllh",
@@ -1665,7 +1678,8 @@  static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.a2w_reg = A2W_PLLH_PIX,
 		.load_mask = CM_PLLH_LOADPIX,
 		.hold_mask = 0,
-		.fixed_divider = 10),
+		.fixed_divider = 10,
+		.flags = CLK_SET_RATE_PARENT),
 
 	/* the clocks */