[PATCH v4 7/8] clk: stm32: Fix stm32f429's ltdc driver hang in set clock rate.

dillon.minfei
2020-05-18T11:10:11Z

fix duplicated ltdc clock register to 'clk_core' case ltdc's clock
turn off by clk_disable_unused()

ltdc set clock rate crashed:
'post_div_data[]''s pll_num is PLL_I2S, PLL_SAI (number is 1,2). but,
as pll_num is offset of 'clks[]' input to clk_register_pll_div(), which
is FCLK, CLK_LSI, defined in 'include/dt-bindings/clock/stm32fx-clock.h'
so, this is a null object at the register time.
then, in ltdc's clock is_enabled(), enable(), will call to_clk_gate().
will return a null object, cause kernel crashed.
need change pll_num to PLL_VCO_I2S, PLL_VCO_SAI for 'post_div_data[]'

duplicated ltdc clock
'stm32f429_gates[]' has a member 'ltdc' register to 'clk_core', but no
upper driver use it, ltdc driver use the lcd-tft defined in
'stm32f429_aux_clk[]'. after system startup, as stm32f429_gates[]'s ltdc
enable_count is zero, so turn off by clk_disable_unused()

Signed-off-by: dillon min <dillon.minfei@gmail.com>
---
Hi Stephen Boyd:

thanks for reviewing, this patch fix the wrong use of clk ignore unused.

thanks.

Changes since V3:
1 drop last wrong changes about 'CLK_IGNORE_UNUSED' patch
2 fix PLL_SAI mismatch with PLL_VCO_SAI
drivers/clk/clk-stm32f4.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c
index 18117ce..fa62e99 100644
--- a/drivers/clk/clk-stm32f4.c
+++ b/drivers/clk/clk-stm32f4.c
@@ -129,7 +129,6 @@ static const struct stm32f4_gate_data stm32f429_gates[] __initconst = {
{ STM32F4_RCC_APB2ENR, 20, "spi5", "apb2_div" },
{ STM32F4_RCC_APB2ENR, 21, "spi6", "apb2_div" },
{ STM32F4_RCC_APB2ENR, 22, "sai1", "apb2_div" },
- { STM32F4_RCC_APB2ENR, 26, "ltdc", "apb2_div" },
};

static const struct stm32f4_gate_data stm32f469_gates[] __initconst = {
@@ -557,13 +556,13 @@ static const struct clk_div_table post_divr_table[] = {

#define MAX_POST_DIV 3
static const struct stm32f4_pll_post_div_data post_div_data[MAX_POST_DIV] = {
- { CLK_I2SQ_PDIV, PLL_I2S, "plli2s-q-div", "plli2s-q",
+ { CLK_I2SQ_PDIV, PLL_VCO_I2S, "plli2s-q-div", "plli2s-q",
CLK_SET_RATE_PARENT, STM32F4_RCC_DCKCFGR, 0, 5, 0, NULL},

- { CLK_SAIQ_PDIV, PLL_SAI, "pllsai-q-div", "pllsai-q",
+ { CLK_SAIQ_PDIV, PLL_VCO_SAI, "pllsai-q-div", "pllsai-q",
CLK_SET_RATE_PARENT, STM32F4_RCC_DCKCFGR, 8, 5, 0, NULL },

- { NO_IDX, PLL_SAI, "pllsai-r-div", "pllsai-r", CLK_SET_RATE_PARENT,
+ { NO_IDX, PLL_VCO_SAI, "pllsai-r-div", "pllsai-r", CLK_SET_RATE_PARENT,
STM32F4_RCC_DCKCFGR, 16, 2, 0, post_divr_table },
};

--
2.7.4