From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from poutre.nerim.net ([62.4.16.124]:54301 "EHLO poutre.nerim.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752297Ab0CSNm4 (ORCPT ); Fri, 19 Mar 2010 09:42:56 -0400 Date: Fri, 19 Mar 2010 14:42:50 +0100 From: Jean Delvare To: Andy Walls , Mauro Carvalho Chehab Cc: Dmitri Belimov , linux-media@vger.kernel.org, "Timothy D. Lenz" Subject: [PATCH] FusionHDTV: Use quick reads for I2C IR device probing Message-ID: <20100319144250.5553055c@hyperion.delvare> In-Reply-To: <20100316120502.3a9323ac@hyperion.delvare> References: <20100301153645.5d529766@glory.loctelecom.ru> <1267442919.3110.20.camel@palomino.walls.org> <20100316120502.3a9323ac@hyperion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On Tue, 16 Mar 2010 12:05:02 +0100, Jean Delvare wrote: > Executive summary (as I understand it): the card that no longer works > is a DViCO FusionHDTV7 Dual Express > (CX23885_BOARD_DVICO_FUSIONHDTV_7_DUAL_EXP), bridge driver cx23885. It > has 2 xc5000 chips at I2C address 0x64 (on 2 different I2C buses, of > course), and an IR chip at 0x6b (on the first of these 2 I2C buses.) > The latter is reported to be missing with recent dvb-v4l trees. > > The first thing to check is whether an ir_video I2C device is created > or not. Look in /sys/bus/i2c/devices, list all the entries there. You > should see two *-0064 entries for the xc5000 chips. You should also > see, but you probably won't, one *-006b entry for the IR chip. The > following command should let us know right away what is there: > > $ grep . /sys/bus/i2c/devices/*/name > > The ir_video device is supposed to be probed by cx23885_i2c_register(). > If it is not created, it means that the probe failed. Maybe these chips > do not like the probe mechanism used by i2c-core (quick write) and only > reply to reads? In that case, we'd need to use reads to detect it. The > i2c core doesn't give us enough control to do this cleanly, but this > could be added if the need exists. In the meantime, we can do the probe > ourselves and instantiate the device unconditionally (by using > i2c_new_device instead of i2c_new_probed_device). We have been debugging over IRC with Timothy, and I have a fix which he tested successfully. Basically, the problem is that the IR device on his chip only replies to read commands, but when switching ir-kbd-i2c to the standard device driver binding model in kernel 2.6.31, I changed the probing method from quick read to quick write as a side effect. This is why the IR device was no longer being detected. Using a quick read again solves the issue. Here comes a fix, tested by Timothy for the cx23885 part, untested for the cx88 part but I'd be very surprised if cx88-based FusionHDTV did not need the exact same fix * * * * * IR support on FusionHDTV cards is broken since kernel 2.6.31. One side effect of the switch to the standard binding model for IR I2C devices was to let i2c-core do the probing instead of the ir-kbd-i2c driver. There is a slight difference between the two probe methods: i2c-core uses 0-byte writes, while the ir-kbd-i2c was using 0-byte reads. As some IR I2C devices only support reads, the new probe method fails to detect them. For now, revert to letting the driver do the probe, using 0-byte reads. In the future, i2c-core will be extended to let callers of i2c_new_probed_device() provide a custom probing function. Signed-off-by: Jean Delvare Tested-by: "Timothy D. Lenz" --- This fix applies to kernels 2.6.31 to 2.6.34. Should be sent to Linus quickly. drivers/media/video/cx23885/cx23885-i2c.c | 12 +++++++++++- drivers/media/video/cx88/cx88-i2c.c | 16 +++++++++++++++- 2 files changed, 26 insertions(+), 2 deletions(-) --- linux-2.6.34-rc1.orig/drivers/media/video/cx23885/cx23885-i2c.c 2010-02-25 09:10:33.000000000 +0100 +++ linux-2.6.34-rc1/drivers/media/video/cx23885/cx23885-i2c.c 2010-03-18 13:33:05.000000000 +0100 @@ -365,7 +365,17 @@ int cx23885_i2c_register(struct cx23885_ memset(&info, 0, sizeof(struct i2c_board_info)); strlcpy(info.type, "ir_video", I2C_NAME_SIZE); - i2c_new_probed_device(&bus->i2c_adap, &info, addr_list); + /* + * We can't call i2c_new_probed_device() because it uses + * quick writes for probing and the IR receiver device only + * replies to reads. + */ + if (i2c_smbus_xfer(&bus->i2c_adap, addr_list[0], 0, + I2C_SMBUS_READ, 0, I2C_SMBUS_QUICK, + NULL) >= 0) { + info.addr = addr_list[0]; + i2c_new_device(&bus->i2c_adap, &info); + } } return bus->i2c_rc; --- linux-2.6.34-rc1.orig/drivers/media/video/cx88/cx88-i2c.c 2010-02-25 09:08:40.000000000 +0100 +++ linux-2.6.34-rc1/drivers/media/video/cx88/cx88-i2c.c 2010-03-18 13:33:05.000000000 +0100 @@ -188,10 +188,24 @@ int cx88_i2c_init(struct cx88_core *core 0x18, 0x6b, 0x71, I2C_CLIENT_END }; + const unsigned short *addrp; memset(&info, 0, sizeof(struct i2c_board_info)); strlcpy(info.type, "ir_video", I2C_NAME_SIZE); - i2c_new_probed_device(&core->i2c_adap, &info, addr_list); + /* + * We can't call i2c_new_probed_device() because it uses + * quick writes for probing and at least some R receiver + * devices only reply to reads. + */ + for (addrp = addr_list; *addrp != I2C_CLIENT_END; addrp++) { + if (i2c_smbus_xfer(&core->i2c_adap, *addrp, 0, + I2C_SMBUS_READ, 0, + I2C_SMBUS_QUICK, NULL) >= 0) { + info.addr = *addrp; + i2c_new_device(&core->i2c_adap, &info); + break; + } + } } return core->i2c_rc; } -- Jean Delvare