[PATCH] spi: omap2-mcspi: add runtime PM to set_cs()

[Sebastian Reichel <sre@xxxxxxxxxx>]

Since commit ddcad7e9068eb omap2_mcspi_set_cs() is called without
runtime power management requested. Thus the below kernel oops may be
generated if a device is accessed after the runtime power management
timeout. This patch fixes the problem by requesting runtime power
management in omap2_mcspi_set_cs().

[   13.933959] Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa09802c
[   13.940490] pgd = cfb38000
[   13.946594] [fa09802c] *pgd=48011452(bad)
[   13.952758] Internal error: : 1028 [#1] PREEMPT ARM
[   13.958862] Modules linked in: tsc2005(+) omap_sham twl4030_wdt omap_wdt
[   13.965332] CPU: 0 PID: 183 Comm: modprobe Not tainted 4.2.0-rc1+ #363
[   13.971801] Hardware name: Nokia RX-51 board
[   13.978302] task: cf572300 ti: cb1f2000 task.ti: cb1f2000
[   13.984924] PC is at omap2_mcspi_set_cs+0x44/0x4c
[   13.991485] LR is at spi_set_cs+0x5c/0x60
[   13.997985] pc : [<c02bd3ac>]    lr : [<c02baecc>]    psr: 20000013
[   13.997985] sp : cb1f3dd0  ip : 00000001  fp : 00000004
[   14.011260] r10: cfce5be8  r9 : 00000fff  r8 : c0654f98
[   14.017913] r7 : 00000000  r6 : 00000000  r5 : 00000000  r4 : 00000000
[   14.024505] r3 : 200103dc  r2 : fa098000  r1 : 00000001  r0 : cf09bc00
[   14.031036] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
[   14.037689] Control: 10c5387d  Table: 8fb38019  DAC: 00000015
[   14.044403] Process modprobe (pid: 183, stack limit = 0xcb1f2210)
[   14.051300] Stack: (0xcb1f3dd0 to 0xcb1f4000)
[   14.058105] 3dc0:                                     cf09bc00 c02bafa4 cf09bc00 cf09bc00
[   14.065277] 3de0: bf013444 bf01254c cf0e2230 cf0e2230 00000001 c0654f98 00000fff 00000fff
[   14.072570] 3e00: 00000008 00000002 00000118 00001f40 00000031 cf09bc00 ffffffed bf013444
[   14.080078] 3e20: 00000031 c0654f98 cb1f2000 00000000 00000000 c02bb5c0 cf09bc00 00000000
[   14.087738] 3e40: bf013454 c027a2f4 00000000 cf09bc00 bf013454 bf013454 00000000 c027a594
[   14.095367] 3e60: 00000000 cf09bc00 cf09bc34 c027a60c bf013454 cb1f3e80 c027a5ac c0278ec8
[   14.102935] 3e80: cf972c4c cf09d630 bf013454 bf013454 cbb55300 c06848d8 00000000 c0279c84
[   14.110473] 3ea0: bf01327c bf01327d 00000000 bf013454 cb889180 00000000 c0654f98 c027b0c8
[   14.117980] 3ec0: 00000000 bf015000 cb889180 c00095b0 0040003e cfe6a080 0040003f 00000000
[   14.125457] 3ee0: 00080000 cfcf9000 cb1f2000 60000013 0040003e cbf1bbc0 00000000 00000001
[   14.132843] 3f00: bf0134cc cb1f2000 bf0134c0 cb1f3f58 00000000 c04352d0 cf801f00 000000d0
[   14.140136] 3f20: bf0134c0 bf0134c0 0000416c cb889040 00000080 c000ebe4 cb1f2000 c0089f68
[   14.147308] 3f40: bf0134c0 cbf1bc00 001a9193 0000416c 001f8d20 c008ab30 d0b10000 0000416c
[   14.154571] 3f60: d0b1267c d0b1252b d0b13514 000016c0 00001ad0 00000000 00000000 00000000
[   14.161865] 3f80: 0000001f 00000020 00000017 00000014 00000012 00000000 00201208 00000000
[   14.169097] 3fa0: 00000000 c000ea60 00201208 00000000 001f8d20 0000416c 001a9193 00000000
[   14.176177] 3fc0: 00201208 00000000 00000000 00000080 00208c20 001a9193 bee09e98 00000000
[   14.183197] 3fe0: b6f742b4 bee09ae4 000153f0 000093e4 60000010 001f8d20 72757463 69665f65
[   14.190277] [<c02bd3ac>] (omap2_mcspi_set_cs) from [<c02baecc>] (spi_set_cs+0x5c/0x60)
[   14.197479] [<c02baecc>] (spi_set_cs) from [<c02bafa4>] (spi_setup+0xd4/0x10c)
[   14.204833] [<c02bafa4>] (spi_setup) from [<bf01254c>] (tsc2005_probe+0x104/0x484 [tsc2005])
[   14.212249] [<bf01254c>] (tsc2005_probe [tsc2005]) from [<c02bb5c0>] (spi_drv_probe+0x50/0x6c)
[   14.219818] [<c02bb5c0>] (spi_drv_probe) from [<c027a2f4>] (really_probe+0xd4/0x230)
[   14.227478] [<c027a2f4>] (really_probe) from [<c027a594>] (driver_probe_device+0x30/0x48)
[   14.235290] [<c027a594>] (driver_probe_device) from [<c027a60c>] (__driver_attach+0x60/0x84)
[   14.243286] [<c027a60c>] (__driver_attach) from [<c0278ec8>] (bus_for_each_dev+0x50/0x84)
[   14.251281] [<c0278ec8>] (bus_for_each_dev) from [<c0279c84>] (bus_add_driver+0xcc/0x1e0)
[   14.259246] [<c0279c84>] (bus_add_driver) from [<c027b0c8>] (driver_register+0x9c/0xe0)
[   14.267272] [<c027b0c8>] (driver_register) from [<c00095b0>] (do_one_initcall+0x100/0x1b0)
[   14.275421] [<c00095b0>] (do_one_initcall) from [<c0089f68>] (do_init_module+0x58/0x1bc)
[   14.283477] [<c0089f68>] (do_init_module) from [<c008ab30>] (SyS_init_module+0x54/0x64)
[   14.291412] [<c008ab30>] (SyS_init_module) from [<c000ea60>] (ret_fast_syscall+0x0/0x3c)
[   14.299407] Code: e5823018 e5902188 e5922000 e582302c (e592302c)
[   14.307403] ---[ end trace d21553dcaefcb5ac ]---

Reported-By: Pali Rohár <pali.rohar@xxxxxxxxx>
Fixes: ddcad7e9068eb (spi: omap2-mcspi: Fix native cs with new set_cs)
Tested-By: Pavel Machek <pavel@xxxxxx>
Signed-off-by: Sebastian Reichel <sre@xxxxxxxxxx>
---
Hi Mark,

Previous discussion about this patch happened in the following thread:

https://lkml.org/lkml/2015/7/11/98

Michael also tested the patch, but have not explicitly written an
Tested-By, so you may want to wait for feedback from him. The patch
should be sent for 4.2-rc, which introduced the regression.

-- Sebastian
---
 drivers/spi/spi-omap2-mcspi.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 5867384..3d09e0b 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -245,6 +245,7 @@ static void omap2_mcspi_set_enable(const struct spi_device *spi, int enable)
 
 static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
 {
+	struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
 	u32 l;
 
 	/* The controller handles the inverted chip selects
@@ -255,6 +256,12 @@ static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
 		enable = !enable;
 
 	if (spi->controller_state) {
+		int err = pm_runtime_get_sync(mcspi->dev);
+		if (err < 0) {
+			dev_err(mcspi->dev, "failed to get sync: %d\n", err);
+			return;
+		}
+
 		l = mcspi_cached_chconf0(spi);
 
 		if (enable)
@@ -263,6 +270,9 @@ static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
 			l |= OMAP2_MCSPI_CHCONF_FORCE;
 
 		mcspi_write_chconf0(spi, l);
+
+		pm_runtime_mark_last_busy(mcspi->dev);
+		pm_runtime_put_autosuspend(mcspi->dev);
 	}
 }
 
-- 
2.1.4

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