From: Mark Brown <broonie@kernel.org>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: Samuel Ortiz <sameo@linux.intel.com>,
Lee Jones <lee.jones@linaro.org>,
Srinivas Ramana <sramana@codeaurora.org>,
linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 3/8] regmap: Add support for using regmap over ssbi
Date: Wed, 11 Dec 2013 00:51:06 +0000 [thread overview]
Message-ID: <20131211005106.GL11468@sirena.org.uk> (raw)
In-Reply-To: <52A7AE1B.3040201@codeaurora.org>
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On Tue, Dec 10, 2013 at 04:13:15PM -0800, Stephen Boyd wrote:
> On 12/10/13 15:50, Mark Brown wrote:
> > On Tue, Dec 10, 2013 at 03:35:18PM -0800, Stephen Boyd wrote:
> >> + reg += sizeof(u16);
> > I'd expect this to generate out of bounds accesses and bad interactions
> > on the bus if we go through the loop more than once since it appears to
> > incrementing the address of reg for every register. I'm also having a
> ssbi_read() just reads the same register x number of times and doesn't
> do any sort of incrementing of address. My understanding was that
> regmap_bulk_read() will read incrementing addresses and then call down
> into this code with the sequential addresses formatted into the reg
> buffer. That was the flaw. Instead we need to take reg and then
That's possibly not the ideal decision for the underlying API, if
nothing else it's confusing naming given what a read function would
normally do.
> increment reg by 1 every time through this loop. Or should we just have
> use_single_rw == true?
No, it doesn't - it increments the address of reg by the size of a
register value each time. Using use_single_rw might make sense, or if
you can't do bulk I/O at all then hooking in via reg_read() and
reg_write() in the config rather than trying to parse out the buffers
might be even better (you can still make helpers to set that up).
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WARNING: multiple messages have this Message-ID (diff)
From: broonie@kernel.org (Mark Brown)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/8] regmap: Add support for using regmap over ssbi
Date: Wed, 11 Dec 2013 00:51:06 +0000 [thread overview]
Message-ID: <20131211005106.GL11468@sirena.org.uk> (raw)
In-Reply-To: <52A7AE1B.3040201@codeaurora.org>
On Tue, Dec 10, 2013 at 04:13:15PM -0800, Stephen Boyd wrote:
> On 12/10/13 15:50, Mark Brown wrote:
> > On Tue, Dec 10, 2013 at 03:35:18PM -0800, Stephen Boyd wrote:
> >> + reg += sizeof(u16);
> > I'd expect this to generate out of bounds accesses and bad interactions
> > on the bus if we go through the loop more than once since it appears to
> > incrementing the address of reg for every register. I'm also having a
> ssbi_read() just reads the same register x number of times and doesn't
> do any sort of incrementing of address. My understanding was that
> regmap_bulk_read() will read incrementing addresses and then call down
> into this code with the sequential addresses formatted into the reg
> buffer. That was the flaw. Instead we need to take reg and then
That's possibly not the ideal decision for the underlying API, if
nothing else it's confusing naming given what a read function would
normally do.
> increment reg by 1 every time through this loop. Or should we just have
> use_single_rw == true?
No, it doesn't - it increments the address of reg by the size of a
register value each time. Using use_single_rw might make sense, or if
you can't do bulk I/O at all then hooking in via reg_read() and
reg_write() in the config rather than trying to parse out the buffers
might be even better (you can still make helpers to set that up).
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next prev parent reply other threads:[~2013-12-11 0:51 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-10 23:35 [PATCH 0/8] Modernize pm8921 with irqdomains + regmap Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-10 23:35 ` [PATCH 1/8] mfd: ssbi: Remove platform data structs and hide ssbi type enum Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:27 ` Lee Jones
2013-12-11 9:27 ` Lee Jones
2013-12-10 23:35 ` [PATCH 2/8] mfd: ssbi: Constify buffer in ssbi_write Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:28 ` Lee Jones
2013-12-11 9:28 ` Lee Jones
2013-12-10 23:35 ` [PATCH 3/8] regmap: Add support for using regmap over ssbi Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-10 23:50 ` Mark Brown
2013-12-10 23:50 ` Mark Brown
2013-12-11 0:13 ` Stephen Boyd
2013-12-11 0:13 ` Stephen Boyd
2013-12-11 0:51 ` Mark Brown [this message]
2013-12-11 0:51 ` Mark Brown
2013-12-11 1:32 ` Stephen Boyd
2013-12-11 1:32 ` Stephen Boyd
2013-12-11 13:27 ` Mark Brown
2013-12-11 13:27 ` Mark Brown
2013-12-12 23:13 ` Stephen Boyd
2013-12-12 23:13 ` Stephen Boyd
2013-12-13 10:41 ` Mark Brown
2013-12-13 10:41 ` Mark Brown
2013-12-13 17:14 ` [PATCH] regmap: Allow regmap_bulk_read() to work for "no-bus" regmaps Stephen Boyd
2013-12-13 17:14 ` Stephen Boyd
2013-12-13 17:14 ` Stephen Boyd
2013-12-16 20:57 ` Mark Brown
2013-12-16 20:57 ` Mark Brown
2013-12-13 21:37 ` [PATCH 3/8] regmap: Add support for using regmap over ssbi Stephen Boyd
2013-12-13 21:37 ` Stephen Boyd
2013-12-16 21:01 ` Mark Brown
2013-12-16 21:01 ` Mark Brown
2013-12-17 2:30 ` [PATCH] regmap: Allow regmap_bulk_write() to work for "no-bus" regmaps Stephen Boyd
2013-12-17 2:30 ` Stephen Boyd
2013-12-18 18:45 ` Mark Brown
2013-12-18 18:45 ` Mark Brown
2013-12-23 20:05 ` Stephen Boyd
2013-12-23 20:05 ` Stephen Boyd
2013-12-24 12:53 ` Mark Brown
2013-12-24 12:53 ` Mark Brown
2013-12-26 19:34 ` Stephen Boyd
2013-12-26 19:34 ` Stephen Boyd
2013-12-26 21:52 ` [PATCH v2] " Stephen Boyd
2013-12-26 21:52 ` Stephen Boyd
2013-12-30 12:42 ` Mark Brown
2013-12-30 12:42 ` Mark Brown
2013-12-10 23:35 ` [PATCH 4/8] mfd: ssbi: Mark match table const Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:29 ` Lee Jones
2013-12-11 9:29 ` Lee Jones
2013-12-10 23:35 ` [PATCH 5/8] mfd: Move pm8xxx-irq.c contents into only driver that uses it Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:35 ` Lee Jones
2013-12-11 9:35 ` Lee Jones
2013-12-12 19:06 ` Stephen Boyd
2013-12-12 19:06 ` Stephen Boyd
2013-12-10 23:35 ` [PATCH 6/8] mfd: pm8921: Update for genirq changes Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:48 ` Lee Jones
2013-12-11 9:48 ` Lee Jones
2013-12-10 23:35 ` [PATCH 7/8] mfd: pm8921: Migrate to irqdomains Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:53 ` Lee Jones
2013-12-11 9:53 ` Lee Jones
2013-12-11 21:30 ` Courtney Cavin
2013-12-11 21:30 ` Courtney Cavin
2013-12-11 21:30 ` Courtney Cavin
2013-12-12 19:05 ` Stephen Boyd
2013-12-12 19:05 ` Stephen Boyd
2013-12-12 19:05 ` Stephen Boyd
2013-12-10 23:35 ` [PATCH 8/8] mfd: pm8921: Use ssbi regmap Stephen Boyd
2013-12-10 23:35 ` Stephen Boyd
2013-12-11 9:55 ` Lee Jones
2013-12-11 9:55 ` Lee Jones
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