[PATCH 01/11] clk: bcm2835: Don't rate change PLLs on behalf of DSI PLL dividers.

Eric Anholt
2016-12-14T19:46:11Z

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

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index b68bf573dcfb..6641030e8eae 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 {
@@ -1201,7 +1202,7 @@ 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)
@@ -1408,7 +1409,8 @@ 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",
@@ -1416,7 +1418,8 @@ 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",
@@ -1432,7 +1435,8 @@ 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(
@@ -1456,7 +1460,8 @@ 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.
@@ -1485,7 +1490,8 @@ 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",
@@ -1493,7 +1499,8 @@ 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",
@@ -1501,7 +1508,8 @@ 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",
@@ -1509,7 +1517,8 @@ 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.
@@ -1538,7 +1547,8 @@ 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",
@@ -1546,7 +1556,8 @@ 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",
@@ -1591,7 +1602,8 @@ 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",
@@ -1599,7 +1611,8 @@ static const struct bcm2835_clk_desc clk_desc_array[] = {
.a2w_reg = A2W_PLLH_AUX,
.load_mask = CM_PLLH_LOADAUX,
.hold_mask = 0,
- .fixed_divider = 10),
+ .fixed_divider = 10,
+ .flags = CLK_SET_RATE_PARENT),
[BCM2835_PLLH_PIX] = REGISTER_PLL_DIV(
.name = "pllh_pix",
.source_pll = "pllh",
@@ -1607,7 +1620,8 @@ 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 */

--
2.11.0