Patch "w1:omap_hdq: fix regression" has been added to the 4.7-stable tree
Subsystems (2)
This is a note to let you know that I've just added the patch titled
w1:omap_hdq: fix regression
to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
w1-omap_hdq-fix-regression.patch
and it can be found in the queue-4.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.
Quoted 1 line
From
ecfaf0c42fc4306b5ec4bf6be01b66f8fe9a9733Mon Sep 17 00:00:00 2001
From: "H. Nikolaus Schaller" <[email protected]>
Date: Tue, 2 Aug 2016 14:07:12 -0700
Subject: w1:omap_hdq: fix regression
From: H. Nikolaus Schaller <[email protected]>
commit ecfaf0c42fc4306b5ec4bf6be01b66f8fe9a9733 upstream.
Commit e93762bbf681 ("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.
--- drivers/w1/masters/omap_hdq.c | 2 -- 1 file changed, 2 deletions(-)
drivers/w1/masters/omap_hdq.c +0 -2
@@ -390,8 +390,6 @@ static int hdq_read_byte(struct hdq_data goto out; } - hdq_data->hdq_irqstatus =0 ; -if (!(hdq_data->hdq_irqstatus &OMAP_HDQ_INT_STATUS_RXCOMPLETE )) { hdq_reg_merge(hdq_data, OMAP_HDQ_CTRL_STATUS, OMAP_HDQ_CTRL_STATUS_DIR | OMAP_HDQ_CTRL_STATUS_GO,
Patches currently in stable-queue which might be from [email protected] are
queue-4.7/w1-omap_hdq-fix-regression.patch