[RFC] clk: imx6: Mark imx_clk_mux as glitchy by default
From: Leonard Crestez
Date: Tue Aug 21 2018 - 15:35:21 EST
With some exceptions clk muxes on imx6 are "glitchy": If the output
is not gated before reparenting then high-frequency pulses can occur and
cause unpredictable behavior. Only a very small subset of muxes are
listed as "glitchless" in the reference manual.
Adapt to this by adding the CLK_SET_PARENT_GATE flag by default to
imx_clk_mux. Add imx_clk_mux_glitchless for the muxes listed as
glitchless and which don't already have have custom behavior.
The CLK_SET_PARENT_GATE flags enables a small check inside the clk core
which make clk_set_parent return -EBUSY if the clock is active. Ensuring
outputs are gated prior to calling set_parent is up to the clk
consumers.
The effect of this patch is that drivers which perform unsafe operations
which mostly work will receive errors instead, possibly breaking
functionality.
Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
---
Unfortunately one of the misbehaving drivers is ldb for LVDS display and
it seems to be a real issue: ldb enable/disable does reparenting on an
active clk used by IPU.
The imx_ldb_encoder_disable function will try to change the parent of
clk_sel to what it was before enabling but at this point the crtc
(inside ipu) is still active. With this patch it gets -EBUSY instead.
This happens because the DRM core disables encoders before crtc (and
backwards on enable). This assumption is reasonable, having an "encoder"
feed a clk back into the "crtc" is odd and needs special handling by the
driver.
Perhaps ipu_di_enable/disable should be handled in atomic_commit_tail
instead of at the crtc level?
More concretely on 6qp-sdb blanking the display happens like this:
* imx_ldb_encoder_disable switches ipu1_di0_sel to ipu1_di0_pre from ldb_di1_podf
* reparenting to ipu1_di0_pre enables it and its parents up to pll5
* possibly glitchy muxing
* ipu_di_disable disables ipu1_di0 (and parents, up to pll5)
---
drivers/clk/imx/clk-imx6q.c | 4 ++--
drivers/clk/imx/clk-imx6sl.c | 2 +-
drivers/clk/imx/clk-imx6sll.c | 2 +-
drivers/clk/imx/clk-imx6sx.c | 2 +-
drivers/clk/imx/clk-imx6ul.c | 2 +-
drivers/clk/imx/clk.h | 16 ++++++++++++----
6 files changed, 18 insertions(+), 10 deletions(-)
diff --git a/drivers/clk/imx/clk-imx6q.c b/drivers/clk/imx/clk-imx6q.c
index 8c7c2fcb8d94..0434d943b1bc 100644
--- a/drivers/clk/imx/clk-imx6q.c
+++ b/drivers/clk/imx/clk-imx6q.c
@@ -547,16 +547,16 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
base = of_iomap(np, 0);
WARN_ON(!base);
/* name reg shift width parent_names num_parents */
clk[IMX6QDL_CLK_STEP] = imx_clk_mux("step", base + 0xc, 8, 1, step_sels, ARRAY_SIZE(step_sels));
- clk[IMX6QDL_CLK_PLL1_SW] = imx_clk_mux("pll1_sw", base + 0xc, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
+ clk[IMX6QDL_CLK_PLL1_SW] = imx_clk_mux_glitchless("pll1_sw", base + 0xc, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
clk[IMX6QDL_CLK_PERIPH_PRE] = imx_clk_mux("periph_pre", base + 0x18, 18, 2, periph_pre_sels, ARRAY_SIZE(periph_pre_sels));
clk[IMX6QDL_CLK_PERIPH2_PRE] = imx_clk_mux("periph2_pre", base + 0x18, 21, 2, periph_pre_sels, ARRAY_SIZE(periph_pre_sels));
clk[IMX6QDL_CLK_PERIPH_CLK2_SEL] = imx_clk_mux("periph_clk2_sel", base + 0x18, 12, 2, periph_clk2_sels, ARRAY_SIZE(periph_clk2_sels));
clk[IMX6QDL_CLK_PERIPH2_CLK2_SEL] = imx_clk_mux("periph2_clk2_sel", base + 0x18, 20, 1, periph2_clk2_sels, ARRAY_SIZE(periph2_clk2_sels));
- clk[IMX6QDL_CLK_AXI_SEL] = imx_clk_mux("axi_sel", base + 0x14, 6, 2, axi_sels, ARRAY_SIZE(axi_sels));
+ clk[IMX6QDL_CLK_AXI_SEL] = imx_clk_mux_glitchless("axi_sel", base + 0x14, 6, 2, axi_sels, ARRAY_SIZE(axi_sels));
clk[IMX6QDL_CLK_ESAI_SEL] = imx_clk_mux("esai_sel", base + 0x20, 19, 2, audio_sels, ARRAY_SIZE(audio_sels));
clk[IMX6QDL_CLK_ASRC_SEL] = imx_clk_mux("asrc_sel", base + 0x30, 7, 2, audio_sels, ARRAY_SIZE(audio_sels));
clk[IMX6QDL_CLK_SPDIF_SEL] = imx_clk_mux("spdif_sel", base + 0x30, 20, 2, audio_sels, ARRAY_SIZE(audio_sels));
if (clk_on_imx6q()) {
clk[IMX6QDL_CLK_GPU2D_AXI] = imx_clk_mux("gpu2d_axi", base + 0x18, 0, 1, gpu_axi_sels, ARRAY_SIZE(gpu_axi_sels));
diff --git a/drivers/clk/imx/clk-imx6sl.c b/drivers/clk/imx/clk-imx6sl.c
index eb6bcbf345a3..0d1aaaafd6f4 100644
--- a/drivers/clk/imx/clk-imx6sl.c
+++ b/drivers/clk/imx/clk-imx6sl.c
@@ -289,11 +289,11 @@ static void __init imx6sl_clocks_init(struct device_node *ccm_node)
WARN_ON(!base);
ccm_base = base;
/* name reg shift width parent_names num_parents */
clks[IMX6SL_CLK_STEP] = imx_clk_mux("step", base + 0xc, 8, 1, step_sels, ARRAY_SIZE(step_sels));
- clks[IMX6SL_CLK_PLL1_SW] = imx_clk_mux("pll1_sw", base + 0xc, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
+ clks[IMX6SL_CLK_PLL1_SW] = imx_clk_mux_glitchless("pll1_sw", base + 0xc, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
clks[IMX6SL_CLK_OCRAM_ALT_SEL] = imx_clk_mux("ocram_alt_sel", base + 0x14, 7, 1, ocram_alt_sels, ARRAY_SIZE(ocram_alt_sels));
clks[IMX6SL_CLK_OCRAM_SEL] = imx_clk_mux("ocram_sel", base + 0x14, 6, 1, ocram_sels, ARRAY_SIZE(ocram_sels));
clks[IMX6SL_CLK_PRE_PERIPH2_SEL] = imx_clk_mux("pre_periph2_sel", base + 0x18, 21, 2, pre_periph_sels, ARRAY_SIZE(pre_periph_sels));
clks[IMX6SL_CLK_PRE_PERIPH_SEL] = imx_clk_mux("pre_periph_sel", base + 0x18, 18, 2, pre_periph_sels, ARRAY_SIZE(pre_periph_sels));
clks[IMX6SL_CLK_PERIPH2_CLK2_SEL] = imx_clk_mux("periph2_clk2_sel", base + 0x18, 20, 1, periph2_clk2_sels, ARRAY_SIZE(periph2_clk2_sels));
diff --git a/drivers/clk/imx/clk-imx6sll.c b/drivers/clk/imx/clk-imx6sll.c
index 52379ee49aec..83bea3b1a416 100644
--- a/drivers/clk/imx/clk-imx6sll.c
+++ b/drivers/clk/imx/clk-imx6sll.c
@@ -182,11 +182,11 @@ static void __init imx6sll_clocks_init(struct device_node *ccm_node)
np = ccm_node;
base = of_iomap(np, 0);
WARN_ON(!base);
clks[IMX6SLL_CLK_STEP] = imx_clk_mux("step", base + 0x0c, 8, 1, step_sels, ARRAY_SIZE(step_sels));
- clks[IMX6SLL_CLK_PLL1_SW] = imx_clk_mux_flags("pll1_sw", base + 0x0c, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels), 0);
+ clks[IMX6SLL_CLK_PLL1_SW] = imx_clk_mux_glitchless("pll1_sw", base + 0x0c, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
clks[IMX6SLL_CLK_AXI_ALT_SEL] = imx_clk_mux("axi_alt_sel", base + 0x14, 7, 1, axi_alt_sels, ARRAY_SIZE(axi_alt_sels));
clks[IMX6SLL_CLK_AXI_SEL] = imx_clk_mux_flags("axi_sel", base + 0x14, 6, 1, axi_sels, ARRAY_SIZE(axi_sels), 0);
clks[IMX6SLL_CLK_PERIPH_PRE] = imx_clk_mux("periph_pre", base + 0x18, 18, 2, periph_pre_sels, ARRAY_SIZE(periph_pre_sels));
clks[IMX6SLL_CLK_PERIPH2_PRE] = imx_clk_mux("periph2_pre", base + 0x18, 21, 2, periph2_pre_sels, ARRAY_SIZE(periph2_pre_sels));
clks[IMX6SLL_CLK_PERIPH_CLK2_SEL] = imx_clk_mux("periph_clk2_sel", base + 0x18, 12, 2, periph_clk2_sels, ARRAY_SIZE(periph_clk2_sels));
diff --git a/drivers/clk/imx/clk-imx6sx.c b/drivers/clk/imx/clk-imx6sx.c
index d9f2890ffe62..c8f2d5aa8a74 100644
--- a/drivers/clk/imx/clk-imx6sx.c
+++ b/drivers/clk/imx/clk-imx6sx.c
@@ -265,11 +265,11 @@ static void __init imx6sx_clocks_init(struct device_node *ccm_node)
base = of_iomap(np, 0);
WARN_ON(!base);
/* name reg shift width parent_names num_parents */
clks[IMX6SX_CLK_STEP] = imx_clk_mux("step", base + 0xc, 8, 1, step_sels, ARRAY_SIZE(step_sels));
- clks[IMX6SX_CLK_PLL1_SW] = imx_clk_mux("pll1_sw", base + 0xc, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
+ clks[IMX6SX_CLK_PLL1_SW] = imx_clk_mux_glitchless("pll1_sw", base + 0xc, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
clks[IMX6SX_CLK_OCRAM_SEL] = imx_clk_mux("ocram_sel", base + 0x14, 6, 2, ocram_sels, ARRAY_SIZE(ocram_sels));
clks[IMX6SX_CLK_PERIPH_PRE] = imx_clk_mux("periph_pre", base + 0x18, 18, 2, periph_pre_sels, ARRAY_SIZE(periph_pre_sels));
clks[IMX6SX_CLK_PERIPH2_PRE] = imx_clk_mux("periph2_pre", base + 0x18, 21, 2, periph2_pre_sels, ARRAY_SIZE(periph2_pre_sels));
clks[IMX6SX_CLK_PERIPH_CLK2_SEL] = imx_clk_mux("periph_clk2_sel", base + 0x18, 12, 2, periph_clk2_sels, ARRAY_SIZE(periph_clk2_sels));
clks[IMX6SX_CLK_PERIPH2_CLK2_SEL] = imx_clk_mux("periph2_clk2_sel", base + 0x18, 20, 1, periph2_clk2_sels, ARRAY_SIZE(periph2_clk2_sels));
diff --git a/drivers/clk/imx/clk-imx6ul.c b/drivers/clk/imx/clk-imx6ul.c
index 361b43f9742e..085c35dfd262 100644
--- a/drivers/clk/imx/clk-imx6ul.c
+++ b/drivers/clk/imx/clk-imx6ul.c
@@ -234,11 +234,11 @@ static void __init imx6ul_clocks_init(struct device_node *ccm_node)
base = of_iomap(np, 0);
WARN_ON(!base);
clks[IMX6UL_CA7_SECONDARY_SEL] = imx_clk_mux("ca7_secondary_sel", base + 0xc, 3, 1, ca7_secondary_sels, ARRAY_SIZE(ca7_secondary_sels));
clks[IMX6UL_CLK_STEP] = imx_clk_mux("step", base + 0x0c, 8, 1, step_sels, ARRAY_SIZE(step_sels));
- clks[IMX6UL_CLK_PLL1_SW] = imx_clk_mux_flags("pll1_sw", base + 0x0c, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels), 0);
+ clks[IMX6UL_CLK_PLL1_SW] = imx_clk_mux_glitchless("pll1_sw", base + 0x0c, 2, 1, pll1_sw_sels, ARRAY_SIZE(pll1_sw_sels));
clks[IMX6UL_CLK_AXI_ALT_SEL] = imx_clk_mux("axi_alt_sel", base + 0x14, 7, 1, axi_alt_sels, ARRAY_SIZE(axi_alt_sels));
clks[IMX6UL_CLK_AXI_SEL] = imx_clk_mux_flags("axi_sel", base + 0x14, 6, 1, axi_sels, ARRAY_SIZE(axi_sels), 0);
clks[IMX6UL_CLK_PERIPH_PRE] = imx_clk_mux("periph_pre", base + 0x18, 18, 2, periph_pre_sels, ARRAY_SIZE(periph_pre_sels));
clks[IMX6UL_CLK_PERIPH2_PRE] = imx_clk_mux("periph2_pre", base + 0x18, 21, 2, periph2_pre_sels, ARRAY_SIZE(periph2_pre_sels));
clks[IMX6UL_CLK_PERIPH_CLK2_SEL] = imx_clk_mux("periph_clk2_sel", base + 0x18, 12, 2, periph_clk2_sels, ARRAY_SIZE(periph_clk2_sels));
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 8076ec040f37..a28268e81824 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -193,12 +193,12 @@ static inline struct clk *imx_clk_gate4(const char *name, const char *parent,
static inline struct clk *imx_clk_mux(const char *name, void __iomem *reg,
u8 shift, u8 width, const char **parents, int num_parents)
{
return clk_register_mux(NULL, name, parents, num_parents,
- CLK_SET_RATE_NO_REPARENT, reg, shift,
- width, 0, &imx_ccm_lock);
+ CLK_SET_RATE_NO_REPARENT | CLK_SET_PARENT_GATE,
+ reg, shift, width, 0, &imx_ccm_lock);
}
static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
u8 shift, u8 width, const char **parents, int num_parents)
{
@@ -210,12 +210,20 @@ static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
static inline struct clk *imx_clk_mux_flags(const char *name,
void __iomem *reg, u8 shift, u8 width, const char **parents,
int num_parents, unsigned long flags)
{
return clk_register_mux(NULL, name, parents, num_parents,
- flags | CLK_SET_RATE_NO_REPARENT, reg, shift, width, 0,
- &imx_ccm_lock);
+ flags | CLK_SET_RATE_NO_REPARENT | CLK_SET_PARENT_GATE,
+ reg, shift, width, 0, &imx_ccm_lock);
+}
+
+static inline struct clk *imx_clk_mux_glitchless(const char *name, void __iomem *reg,
+ u8 shift, u8 width, const char **parents, int num_parents)
+{
+ return clk_register_mux(NULL, name, parents, num_parents,
+ CLK_SET_RATE_NO_REPARENT,
+ reg, shift, width, 0, &imx_ccm_lock);
}
struct clk *imx_clk_cpu(const char *name, const char *parent_name,
struct clk *div, struct clk *mux, struct clk *pll,
struct clk *step);
--
2.17.1