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From: Devin Heitmueller <dheitmueller@kernellabs.com>
To: linux-media@vger.kernel.org
Cc: Devin Heitmueller <dheitmueller@kernellabs.com>
Subject: [PATCH 20/24] au0828: tweak workaround for i2c clock stretching bug
Date: Mon,  6 Aug 2012 22:47:10 -0400	[thread overview]
Message-ID: <1344307634-11673-21-git-send-email-dheitmueller@kernellabs.com> (raw)
In-Reply-To: <1344307634-11673-1-git-send-email-dheitmueller@kernellabs.com>

The hack I put in a couple of years ago to avoid clock stretching issues
when talking to the xc5000 worked fine for writes, but intermittently fails
for register reads, because the xc5000 may stretch the clock for longer
between bytes (I was seeing cases of 21 us on the analyzer).

The problem manifested itself as the xc5000 firmware version and PLL lock
register intermittently showing garbage values.

Slow down the i2c bus from 30 KHz to 20 KHz to accommodate.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
---
 drivers/media/video/au0828/au0828-cards.c |    4 ++--
 drivers/media/video/au0828/au0828-reg.h   |    1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/video/au0828/au0828-cards.c b/drivers/media/video/au0828/au0828-cards.c
index 1c6015a..4a09b0e 100644
--- a/drivers/media/video/au0828/au0828-cards.c
+++ b/drivers/media/video/au0828/au0828-cards.c
@@ -46,7 +46,7 @@ struct au0828_board au0828_boards[] = {
 		.name	= "Hauppauge HVR850",
 		.tuner_type = TUNER_XC5000,
 		.tuner_addr = 0x61,
-		.i2c_clk_divider = AU0828_I2C_CLK_30KHZ,
+		.i2c_clk_divider = AU0828_I2C_CLK_20KHZ,
 		.input = {
 			{
 				.type = AU0828_VMUX_TELEVISION,
@@ -77,7 +77,7 @@ struct au0828_board au0828_boards[] = {
 		   stretch fits inside of a normal clock cycle, or else the
 		   au0828 fails to set the STOP bit.  A 30 KHz clock puts the
 		   clock pulse width at 18us */
-		.i2c_clk_divider = AU0828_I2C_CLK_30KHZ,
+		.i2c_clk_divider = AU0828_I2C_CLK_20KHZ,
 		.input = {
 			{
 				.type = AU0828_VMUX_TELEVISION,
diff --git a/drivers/media/video/au0828/au0828-reg.h b/drivers/media/video/au0828/au0828-reg.h
index c39f3d2..2140f4c 100644
--- a/drivers/media/video/au0828/au0828-reg.h
+++ b/drivers/media/video/au0828/au0828-reg.h
@@ -63,3 +63,4 @@
 #define AU0828_I2C_CLK_250KHZ 0x07
 #define AU0828_I2C_CLK_100KHZ 0x14
 #define AU0828_I2C_CLK_30KHZ  0x40
+#define AU0828_I2C_CLK_20KHZ  0x60
-- 
1.7.1


  parent reply	other threads:[~2012-08-07  2:48 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-07  2:46 [PATCH 00/24] Various HVR-950q and xc5000 fixes Devin Heitmueller
2012-08-07  2:46 ` [PATCH 01/24] au8522: fix intermittent lockup of analog video decoder Devin Heitmueller
2012-08-07  2:46 ` [PATCH 02/24] au8522: Fix off-by-one in SNR table for QAM256 Devin Heitmueller
2012-08-07  2:46 ` [PATCH 03/24] au8522: properly recover from the au8522 delivering misaligned TS streams Devin Heitmueller
2012-08-07  2:46 ` [PATCH 04/24] au0828: Make the s_reg and g_reg advanced debug calls work against the bridge Devin Heitmueller
2012-08-07  2:46 ` [PATCH 05/24] xc5000: properly show quality register values Devin Heitmueller
2012-08-07  2:46 ` [PATCH 06/24] xc5000: add support for showing the SNR and gain in the debug output Devin Heitmueller
2012-08-07  2:46 ` [PATCH 07/24] xc5000: properly report i2c write failures Devin Heitmueller
     [not found]   ` <CAPLVkLv6JNvSdSFCY7YNRkmfzHv5+JD7Y5hxvjxdFtRT2JgE2A@mail.gmail.com>
2014-02-07 13:46     ` Devin Heitmueller
2014-02-10  8:25       ` Joonyoung Shim
2014-02-10 13:29         ` Devin Heitmueller
2012-08-07  2:46 ` [PATCH 08/24] au0828: fix race condition that causes xc5000 to not bind for digital Devin Heitmueller
2012-08-07  2:46 ` [PATCH 09/24] au0828: make sure video standard is setup in tuner-core Devin Heitmueller
2012-08-07  2:47 ` [PATCH 10/24] au8522: fix regression in logging introduced by separation of modules Devin Heitmueller
2012-08-07  2:47 ` [PATCH 11/24] xc5000: don't invoke auto calibration unless we really did reset tuner Devin Heitmueller
2012-08-07  2:47 ` [PATCH 12/24] au0828: prevent i2c gate from being kept open while in analog mode Devin Heitmueller
2012-08-07  2:47 ` [PATCH 13/24] au0828: fix case where STREAMOFF being called on stopped stream causes BUG() Devin Heitmueller
2012-08-07  2:47 ` [PATCH 14/24] au0828: speed up i2c clock when doing xc5000 firmware load Devin Heitmueller
2012-08-07  2:47 ` [PATCH 15/24] au0828: remove control buffer from send_control_msg Devin Heitmueller
2012-08-07  2:47 ` [PATCH 16/24] au0828: tune retry interval for i2c interaction Devin Heitmueller
2012-08-07  2:47 ` [PATCH 17/24] au0828: fix possible race condition in usage of dev->ctrlmsg Devin Heitmueller
2012-08-09 23:48   ` Mauro Carvalho Chehab
2012-08-10  0:57     ` Devin Heitmueller
2012-08-07  2:47 ` [PATCH 18/24] xc5000: reset device if encountering PLL lock failure Devin Heitmueller
2012-08-07  2:47 ` [PATCH 19/24] xc5000: add support for firmware load check and init status Devin Heitmueller
2012-08-07  2:47 ` Devin Heitmueller [this message]
2012-08-07  2:47 ` [PATCH 21/24] xc5000: show debug version fields in decimal instead of hex Devin Heitmueller
2012-08-07  2:47 ` [PATCH 22/24] au0828: fix a couple of missed edge cases for i2c gate with analog Devin Heitmueller
2012-08-07  2:47 ` [PATCH 23/24] au0828: make xc5000 firmware speedup apply to the xc5000c as well Devin Heitmueller
2012-08-07  2:47 ` [PATCH 24/24] xc5000: change filename to production/redistributable xc5000c firmware Devin Heitmueller
2012-08-07  6:26 ` [PATCH 00/24] Various HVR-950q and xc5000 fixes Hans Verkuil
2012-08-07 12:48   ` Devin Heitmueller
2012-08-07 12:59     ` Hans Verkuil

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