From 0e8bac9791b1539b72b8049b18218eb762d94d71 Mon Sep 17 00:00:00 2001 From: Matthias Schwarzott Date: Fri, 24 Oct 2008 10:47:07 -0300 Subject: [PATCH] V4L/DVB (9357): cx88-dvb: Fix Oops in case i2c bus failed to register There already is an report at kernel bugzilla about this issue: http://bugzilla.kernel.org/show_bug.cgi?id=9455 When enabling extra checks for the i2c-bus of cx88 based cards by loading i2c_algo_bit with bit_test=1 this may trigger an oops when loading cx88_dvb. This is caused by the extra check code that detects that the sda-line is stuck high and thus does not register the i2c-bus. cx88-dvb however does not check if the i2c-bus is valid and just uses core->i2c_adap to attach dvb frontend modules. This leads to an oops at the first call to i2c_transfer: $ modprobe i2c_algo_bit bit_test=1 $ modprobe cx8802 cx88/2: cx2388x MPEG-TS Driver Manager version 0.0.6 loaded cx88[0]: quirk: PCIPCI_NATOMA -- set TBFX cx88[0]: subsystem: 0070:9202, board: Hauppauge Nova-S-Plus DVB-S [card=37,autodetected], frontend(s): 1 cx88[0]: TV tuner type 4, Radio tuner type -1 cx88[0]: SDA stuck high! cx88[0]: i2c register FAILED input: cx88 IR (Hauppauge Nova-S-Plus as /class/input/input5 cx88[0]/2: cx2388x 8802 Driver Manager cx88-mpeg driver manager 0000:00:10.2: enabling device (0154 -> 0156) cx88-mpeg driver manager 0000:00:10.2: PCI INT A -> Link[LNKD] -> GSI 9 (level, low) -> IRQ 9 cx88[0]/2: found at 0000:00:10.2, rev: 5, irq: 9, latency: 64, mmio: 0xfb000000 cx8802_probe() allocating 1 frontend(s) cx88/2: cx2388x dvb driver version 0.0.6 loaded cx88/2: registering cx8802 driver, type: dvb access: shared cx88[0]/2: subsystem: 0070:9202, board: Hauppauge Nova-S-Plus DVB-S [card=37] cx88[0]/2: cx2388x based DVB/ATSC card BUG: unable to handle kernel NULL pointer dereference at 00000000 IP: [] :i2c_core:i2c_transfer+0x1f/0x80 *pde = 00000000 Modules linked in: cx88_dvb(+) cx8802 cx88xx ir_common i2c_algo_bit tveeprom videobuf_dvb btcx_risc mga drm ipv6 fscpos eeprom nfsd exportfs stv0299 b2c2_flexcop_pci b2c2_flexcop cx24123 s5h1420 ves1x93 dvb_ttpci dvb_core saa7146_vv saa7146 videobuf_dma_sg videobuf_core videodev v4l1_compat ttpci_eeprom lirc_serial lirc_dev usbhid rtc uhci_hcd 8139too i2c_piix4 i2c_core usbcore evdev Pid: 4249, comm: modprobe Not tainted (2.6.27-gentoo #3) EIP: 0060:[] EFLAGS: 00010296 CPU: 0 EIP is at i2c_transfer+0x1f/0x80 [i2c_core] EAX: 00000000 EBX: ffffffa1 ECX: 00000002 EDX: d6c71e3c ESI: d80cd050 EDI: d8093c00 EBP: d6c71e20 ESP: d6c71e0c DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/cx88/cx88-dvb.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/media/video/cx88/cx88-dvb.c b/drivers/media/video/cx88/cx88-dvb.c index cf6c30d4e545..309ca5e68063 100644 --- a/drivers/media/video/cx88/cx88-dvb.c +++ b/drivers/media/video/cx88/cx88-dvb.c @@ -598,6 +598,11 @@ static int dvb_register(struct cx8802_dev *dev) struct videobuf_dvb_frontend *fe0, *fe1 = NULL; int mfe_shared = 0; /* bus not shared by default */ + if (0 != core->i2c_rc) { + printk(KERN_ERR "%s/2: no i2c-bus available, cannot attach dvb drivers\n", core->name); + goto frontend_detach; + } + /* Get the first frontend */ fe0 = videobuf_dvb_get_frontend(&dev->frontends, 1); if (!fe0)