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clk: imx6: Make the LDB_DI0 and LDB_DI1 clocks read-only 

Due to incorrect placement of the clock gate cell in the ldb_di[x]_clk
tree, the glitchy parent mux of ldb_di[x]_clk can cause a glitch to
enter the ldb_di_ipu_div divider. If the divider gets locked up, no
ldb_di[x]_clk is generated, and the LVDS display will hang when the
ipu_di_clk is sourced from ldb_di_clk.

To fix the problem, both the new and current parent of the ldb_di_clk
should be disabled before the switch. As this can not be guaranteed by
the clock framework during runtime, make the ldb_di[x]_sel muxes read-only.
A workaround to set the muxes once during boot could be added to the
kernel or bootloader.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This commit is contained in:
Philipp Zabel 2016-10-17 22:29:13 -02:00 committed by Shawn Guo
parent f13abeff2c
commit 03d576f202
2 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/clk/imx/clk-imx6q.c
View File

@ -345,8 +345,8 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
clk[IMX6QDL_CLK_GPU3D_SHADER_SEL] = imx_clk_mux("gpu3d_shader_sel", base + 0x18, 8, 2, gpu3d_shader_sels, ARRAY_SIZE(gpu3d_shader_sels));
clk[IMX6QDL_CLK_IPU1_SEL] = imx_clk_mux("ipu1_sel", base + 0x3c, 9, 2, ipu_sels, ARRAY_SIZE(ipu_sels));
clk[IMX6QDL_CLK_IPU2_SEL] = imx_clk_mux("ipu2_sel", base + 0x3c, 14, 2, ipu_sels, ARRAY_SIZE(ipu_sels));
clk[IMX6QDL_CLK_LDB_DI0_SEL] = imx_clk_mux_flags("ldb_di0_sel", base + 0x2c, 9, 3, ldb_di_sels, ARRAY_SIZE(ldb_di_sels), CLK_SET_RATE_PARENT);
clk[IMX6QDL_CLK_LDB_DI1_SEL] = imx_clk_mux_flags("ldb_di1_sel", base + 0x2c, 12, 3, ldb_di_sels, ARRAY_SIZE(ldb_di_sels), CLK_SET_RATE_PARENT);
clk[IMX6QDL_CLK_LDB_DI0_SEL] = imx_clk_mux_ldb("ldb_di0_sel", base + 0x2c, 9, 3, ldb_di_sels, ARRAY_SIZE(ldb_di_sels));
clk[IMX6QDL_CLK_LDB_DI1_SEL] = imx_clk_mux_ldb("ldb_di1_sel", base + 0x2c, 12, 3, ldb_di_sels, ARRAY_SIZE(ldb_di_sels));
clk[IMX6QDL_CLK_IPU1_DI0_PRE_SEL] = imx_clk_mux_flags("ipu1_di0_pre_sel", base + 0x34, 6, 3, ipu_di_pre_sels, ARRAY_SIZE(ipu_di_pre_sels), CLK_SET_RATE_PARENT);
clk[IMX6QDL_CLK_IPU1_DI1_PRE_SEL] = imx_clk_mux_flags("ipu1_di1_pre_sel", base + 0x34, 15, 3, ipu_di_pre_sels, ARRAY_SIZE(ipu_di_pre_sels), CLK_SET_RATE_PARENT);
clk[IMX6QDL_CLK_IPU2_DI0_PRE_SEL] = imx_clk_mux_flags("ipu2_di0_pre_sel", base + 0x38, 6, 3, ipu_di_pre_sels, ARRAY_SIZE(ipu_di_pre_sels), CLK_SET_RATE_PARENT);
@ -597,12 +597,6 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
clk_register_clkdev(clk[IMX6QDL_CLK_ENET_REF], "enet_ref", NULL);
if ((imx_get_soc_revision() != IMX_CHIP_REVISION_1_0) ||
clk_on_imx6dl()) {
clk_set_parent(clk[IMX6QDL_CLK_LDB_DI0_SEL], clk[IMX6QDL_CLK_PLL5_VIDEO_DIV]);
clk_set_parent(clk[IMX6QDL_CLK_LDB_DI1_SEL], clk[IMX6QDL_CLK_PLL5_VIDEO_DIV]);
}
clk_set_rate(clk[IMX6QDL_CLK_PLL3_PFD1_540M], 540000000);
if (clk_on_imx6dl())
clk_set_parent(clk[IMX6QDL_CLK_IPU1_SEL], clk[IMX6QDL_CLK_PLL3_PFD1_540M]);

8
drivers/clk/imx/clk.h
View File

@ -75,6 +75,14 @@ static inline struct clk *imx_clk_fixed(const char *name, int rate)
return clk_register_fixed_rate(NULL, name, NULL, 0, rate);
}
static inline struct clk *imx_clk_mux_ldb(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 | CLK_SET_RATE_PARENT, reg,
shift, width, CLK_MUX_READ_ONLY, &imx_ccm_lock);
}
static inline struct clk *imx_clk_fixed_factor(const char *name,
const char *parent, unsigned int mult, unsigned int div)
{