[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>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index bbc8e3a7ff556c1eb8306b56169f2e36c28d0f14..490173611d6b615013b2d87a7984af9aec7b04d2 100644 (file)
--- 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: