-stable review patch. If anyone has any objections, please let us know. ------------------ From: Maxime Bizon 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: [] (mv64xxx_i2c_intr+0x0/0x2b8) from [] (__do_irq+0x4c/0x8c) [] (__do_irq+0x0/0x8c) from [] (do_level_IRQ+0x68/0xc0) r8 = C0501E08 r7 = 00000005 r6 = C0501E08 r5 = 00000005 r4 = C048BB78 [] (do_level_IRQ+0x0/0xc0) from [] (asm_do_IRQ+0x50/0x134) r6 = C0449C78 r5 = F1020000 r4 = FFFFFFFF [] (asm_do_IRQ+0x0/0x134) from [] (__irq_svc+0x24/0x100) r8 = C1CAC400 r7 = 00000005 r6 = 00000002 r5 = F1020000 r4 = FFFFFFFF [] (setup_irq+0x0/0x124) from [] (request_irq+0xb0/0xd0) r7 = C041B2AC r6 = C0397E4C r5 = 00000000 r4 = 00000005 [] (request_irq+0x0/0xd0) from [] (mv64xxx_i2c_probe+0x148/0x244) [] (mv64xxx_i2c_probe+0x0/0x244) from [] (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 Acked-by: Mark A. Greer Signed-off-by: Jean Delvare Signed-off-by: Chris Wright --- Merged in 2.6.20-rc4: http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=3269bb63eb076318ce4fb554851d047e1c9aa1a5 drivers/i2c/busses/i2c-mv64xxx.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- linux-2.6.19.2.orig/drivers/i2c/busses/i2c-mv64xxx.c +++ linux-2.6.19.2/drivers/i2c/busses/i2c-mv64xxx.c @@ -529,6 +529,8 @@ mv64xxx_i2c_probe(struct platform_device 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 goto exit_free_irq; } - mv64xxx_i2c_hw_init(drv_data); - return 0; exit_free_irq: -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/