4.9-stable review patch. If anyone has any objections, please let me know.
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From: Tony Lindgren tony@atomide.com
commit 5ae51d67aec95f6f9386aa8dd5db424964895575 upstream.
I noticed that modprobe clk-twl6040 can fail after a cold boot with: abe_cm:clk:0010:0: failed to enable ... Unhandled fault: imprecise external abort (0x1406) at 0xbe896b20
WARNING: CPU: 1 PID: 29 at drivers/clk/clk.c:828 clk_core_disable_lock+0x18/0x24 ... (clk_core_disable_lock) from [<c0123534>] (_disable_clocks+0x18/0x90) (_disable_clocks) from [<c0124040>] (_idle+0x17c/0x244) (_idle) from [<c0125ad4>] (omap_hwmod_idle+0x24/0x44) (omap_hwmod_idle) from [<c053a038>] (sysc_runtime_suspend+0x48/0x108) (sysc_runtime_suspend) from [<c06084c4>] (__rpm_callback+0x144/0x1d8) (__rpm_callback) from [<c0608578>] (rpm_callback+0x20/0x80) (rpm_callback) from [<c0607034>] (rpm_suspend+0x120/0x694) (rpm_suspend) from [<c0607a78>] (__pm_runtime_idle+0x60/0x84) (__pm_runtime_idle) from [<c053aaf0>] (sysc_probe+0x874/0xf2c) (sysc_probe) from [<c05fecd4>] (platform_drv_probe+0x48/0x98)
After searching around for a similar issue, I came across an earlier fix that never got merged upstream in the Android tree for glass-omap-xrr02. There is patch "MFD: twl6040-codec: Implement PDMCLK cold temp errata" by Misael Lopez Cruz misael.lopez@ti.com.
Based on my observations, this fix is also needed when cold booting devices, and not just for deeper idle modes. Since we now have a clock driver for pdmclk, let's fix the issue in twl6040_pdmclk_prepare().
Cc: Misael Lopez Cruz misael.lopez@ti.com Cc: Peter Ujfalusi peter.ujfalusi@ti.com Signed-off-by: Tony Lindgren tony@atomide.com Acked-by: Peter Ujfalusi peter.ujfalusi@ti.com Cc: stable@vger.kernel.org Signed-off-by: Stephen Boyd sboyd@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/clk/clk-twl6040.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 51 insertions(+), 2 deletions(-)
--- a/drivers/clk/clk-twl6040.c +++ b/drivers/clk/clk-twl6040.c @@ -41,6 +41,43 @@ static int twl6040_pdmclk_is_prepared(st return pdmclk->enabled; }
+static int twl6040_pdmclk_reset_one_clock(struct twl6040_pdmclk *pdmclk, + unsigned int reg) +{ + const u8 reset_mask = TWL6040_HPLLRST; /* Same for HPPLL and LPPLL */ + int ret; + + ret = twl6040_set_bits(pdmclk->twl6040, reg, reset_mask); + if (ret < 0) + return ret; + + ret = twl6040_clear_bits(pdmclk->twl6040, reg, reset_mask); + if (ret < 0) + return ret; + + return 0; +} + +/* + * TWL6040A2 Phoenix Audio IC erratum #6: "PDM Clock Generation Issue At + * Cold Temperature". This affects cold boot and deeper idle states it + * seems. The workaround consists of resetting HPPLL and LPPLL. + */ +static int twl6040_pdmclk_quirk_reset_clocks(struct twl6040_pdmclk *pdmclk) +{ + int ret; + + ret = twl6040_pdmclk_reset_one_clock(pdmclk, TWL6040_REG_HPPLLCTL); + if (ret) + return ret; + + ret = twl6040_pdmclk_reset_one_clock(pdmclk, TWL6040_REG_LPPLLCTL); + if (ret) + return ret; + + return 0; +} + static int twl6040_pdmclk_prepare(struct clk_hw *hw) { struct twl6040_pdmclk *pdmclk = container_of(hw, struct twl6040_pdmclk, @@ -48,8 +85,20 @@ static int twl6040_pdmclk_prepare(struct int ret;
ret = twl6040_power(pdmclk->twl6040, 1); - if (!ret) - pdmclk->enabled = 1; + if (ret) + return ret; + + ret = twl6040_pdmclk_quirk_reset_clocks(pdmclk); + if (ret) + goto out_err; + + pdmclk->enabled = 1; + + return 0; + +out_err: + dev_err(pdmclk->dev, "%s: error %i\n", __func__, ret); + twl6040_power(pdmclk->twl6040, 0);
return ret; }