linux-kernel - Re: [PATCH V1 1/2] mfd: tps65910: use regmap for device register access.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120208130726.GB5943@opensource.wolfsonmicro.com>
Date:	Wed, 8 Feb 2012 13:07:26 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Laxman Dewangan <ldewangan@...dia.com>
Cc:	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"lrg@...com" <lrg@...com>,
	"jedu@...mlogic.co.uk" <jedu@...mlogic.co.uk>,
	"gg@...mlogic.co.uk" <gg@...mlogic.co.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH V1 1/2] mfd: tps65910: use regmap for device register
 access.

On Wed, Feb 08, 2012 at 05:45:43PM +0530, Laxman Dewangan wrote:
> On Wednesday 08 February 2012 05:11 PM, Mark Brown wrote:

> >This is *really* odd.  Why is this not static data (or mostly static
> >data), why does it vary at runtime?

> I did not wanted to make the list of register in core driver. Wanted
> to leave the decision to the sub-devices driver where they need to
> enable cache based on their requirements.
> Do you think that the register list (although it is used in the
> regulator driver) should be in the core file? If this is allow then
> I can make the static table in core driver.

Yes, it should be in the core driver.

> >>+	/* If any of register is non-volatile then use byte-wise transfer */
> >>+	for (i = 0; i<  bytes; ++i) {
> >>+		ival = (unsigned int) (*wbuf++);
> >>+		ret = regmap_write(tps65910->regmap, reg, ival);
> >>+		if (ret<  0)
> >>+			return ret;
> >>+	}

> >There's nothing specific to the driver about this, if this is a good
> >idea add support for it to the core.

> This function added because there is no bulk_write function in core
> driver which supports the non-volatile in the list. Even if number
> of bytes read is 1.
> Should we move the above logic to core driver?

This is the core driver?  If you mean the regmap core then yes.

> - If any of the register is non-volatile in bulk write then split
> the transfer into the byte-wise/short-wise/long-wise
> (format.val_bytes) based on register width?
> - If all register is volatile the uses the regmap_raw_write()

> Does it sounds reasonable? If yes then I can move this code to
> regmap.c as regmap_bulk_write() i.e. new function.

Yes, though bulk_write() is tricky as it's *really* unclear what it
should take as an argument - should it be raw register size (in which
case it's just raw_write()) or should it be ints (in which case it needs
to repack the data too)?  I suspect ints but I'm really not convinced
there's much use case for this.

Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)