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

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Message-Id: <1589800165-3271-8-git-send-email-dillon.minfei@gmail.com>
Date:   Mon, 18 May 2020 19:09:24 +0800
From:   dillon.minfei@...il.com
To:     robh+dt@...nel.org, p.zabel@...gutronix.de,
        mcoquelin.stm32@...il.com, broonie@...nel.org,
        devicetree@...r.kernel.org, alexandre.torgue@...com,
        thierry.reding@...il.com, sam@...nborg.org, airlied@...ux.ie,
        daniel@...ll.ch, mturquette@...libre.com, sboyd@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-spi@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        dri-devel@...ts.freedesktop.org, linux-clk@...r.kernel.org,
        dillon min <dillon.minfei@...il.com>
Subject: [PATCH v4 7/8] clk: stm32: Fix stm32f429's ltdc driver hang in set clock rate.

From: dillon min <dillon.minfei@...il.com>

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@...il.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