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@nxp.com

---

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);