From 3269bb63eb076318ce4fb554851d047e1c9aa1a5 Mon Sep 17 00:00:00 2001 From: Maxime Bizon <mbizon@freebox.fr> Date: Fri, 5 Jan 2007 17:54:05 +0100 Subject: [PATCH] i2c-mv64xxx: Fix random oops at boot I have a Marvell board which has the same i2c hw block than mv64xxx, so I'm trying to use i2c-mv64xxx driver. But I get the following random oops at boot: Unable to handle kernel NULL pointer dereference at virtual address 00000002 Backtrace: [<c0397e4c>] (mv64xxx_i2c_intr+0x0/0x2b8) from [<c02879c4>] (__do_irq+0x4c/0x8c) [<c0287978>] (__do_irq+0x0/0x8c) from [<c0287c0c>] (do_level_IRQ+0x68/0xc0) r8 = C0501E08 r7 = 00000005 r6 = C0501E08 r5 = 00000005 r4 = C048BB78 [<c0287ba4>] (do_level_IRQ+0x0/0xc0) from [<c02885f8>] (asm_do_IRQ+0x50/0x134) r6 = C0449C78 r5 = F1020000 r4 = FFFFFFFF [<c02885a8>] (asm_do_IRQ+0x0/0x134) from [<c02869c4>] (__irq_svc+0x24/0x100) r8 = C1CAC400 r7 = 00000005 r6 = 00000002 r5 = F1020000 r4 = FFFFFFFF [<c0287efc>] (setup_irq+0x0/0x124) from [<c02880d0>] (request_irq+0xb0/0xd0) r7 = C041B2AC r6 = C0397E4C r5 = 00000000 r4 = 00000005 [<c0288020>] (request_irq+0x0/0xd0) from [<c03985f4>] (mv64xxx_i2c_probe+0x148/0x244) [<c03984ac>] (mv64xxx_i2c_probe+0x0/0x244) from [<c038bedc>] (platform_drv_probe+0x20/0x24) The oops is caused by a spurious interrupt that occurs when request_irq is called. mv64xxx_i2c_fsm() tries to read drv_data->msg, which is NULL. I noticed that hardware init is done after requesting irq. Thus any pending irq from previous hardware usage may cause this. The following patch fixes it: Signed-off-by: Maxime Bizon <mbizon@freebox.fr> Acked-by: Mark A. Greer <mgreer@mvista.com> Signed-off-by: Jean Delvare <khali@linux-fr.org> --- drivers/i2c/busses/i2c-mv64xxx.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c index bbc8e3a7ff55..490173611d6b 100644 --- a/drivers/i2c/busses/i2c-mv64xxx.c +++ b/drivers/i2c/busses/i2c-mv64xxx.c @@ -529,6 +529,8 @@ mv64xxx_i2c_probe(struct platform_device *pd) platform_set_drvdata(pd, drv_data); i2c_set_adapdata(&drv_data->adapter, drv_data); + mv64xxx_i2c_hw_init(drv_data); + if (request_irq(drv_data->irq, mv64xxx_i2c_intr, 0, MV64XXX_I2C_CTLR_NAME, drv_data)) { dev_err(&drv_data->adapter.dev, @@ -542,8 +544,6 @@ mv64xxx_i2c_probe(struct platform_device *pd) goto exit_free_irq; } - mv64xxx_i2c_hw_init(drv_data); - return 0; exit_free_irq: -- GitLab