AuxXxilium/linux_dsm_epyc7002
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linux_dsm_epyc7002/drivers/w1
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H. Nikolaus Schaller ecfaf0c42f w1:omap_hdq: fix regression 
Commit e93762bbf6 ("w1: masters: omap_hdq: add support for 1-wire
mode") added a statement to clear the hdq_irqstatus flags in
hdq_read_byte().

If the hdq reading process is scheduled slowly or interrupts are
disabled for a while the hardware read activity might already be
finished on entry of hdq_read_byte().  And hdq_isr() already has set the
hdq_irqstatus to 0x6 (can be seen in debug mode) denoting that both, the
TXCOMPLETE and RXCOMPLETE interrupts occurred in parallel.

This means there is no need to wait and the hdq_read_byte() can just
read the byte from the hdq controller.

By resetting hdq_irqstatus to 0 the read process is forced to be always
waiting again (because the if statement always succeeds) but the
hardware will not issue another RXCOMPLETE interrupt.  This results in a
false timeout.

After such a situation the hdq bus hangs.

Link: http://lkml.kernel.org/r/b724765f87ad276a69625bc19806c8c8844c4590.1469513669.git.hns@goldelico.com
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-02 19:35:40 -04:00
..
masters w1:omap_hdq: fix regression 2016-08-02 19:35:40 -04:00
slaves w1: add helper macro module_w1_family 2016-08-02 19:35:39 -04:00
Kconfig
Makefile
w1_family.c w1: use pr_* instead of printk 2014-06-19 17:46:51 -07:00
w1_family.h w1: add helper macro module_w1_family 2016-08-02 19:35:39 -04:00
w1_int.c drivers/w1/w1_int.c: call put_device if device_register fails 2015-10-05 04:47:09 +01:00
w1_int.h
w1_io.c w1: Spelling s/minmum/minimum/ 2016-05-01 14:04:19 -07:00
w1_log.h w1: use pr_* instead of printk 2014-06-19 17:46:51 -07:00
w1_netlink.c w1: avoid potential u16 overflow 2014-11-26 19:09:01 -08:00
w1_netlink.h w1: optional bundling of netlink kernel replies 2014-05-27 13:56:21 -07:00
w1.c w1: silence an uninitialized variable warning 2016-05-01 14:04:19 -07:00
w1.h w1: add ability to set (SRAM) and store (EEPROM) configuration for temp sensors like DS18B20 2016-05-01 14:37:49 -07:00