linux-kernel - Re: [PATCH] spi: tegra114: add spi driver

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: <20130220131112.GE2726@opensource.wolfsonmicro.com>
Date:	Wed, 20 Feb 2013 13:11:12 +0000
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Laxman Dewangan <ldewangan@...dia.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"spi-devel-general@...ts.sourceforge.net" 
	<spi-devel-general@...ts.sourceforge.net>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	Stephen Warren <swarren@...dia.com>
Subject: Re: [PATCH] spi: tegra114: add spi driver

On Wed, Feb 20, 2013 at 05:59:03PM +0530, Laxman Dewangan wrote:
> On Tuesday 19 February 2013 11:46 PM, Stephen Warren wrote:

> >In the older Tegra SPI drivers, the PM runtime logic was was of
> >master->{un,}prepare_transfer. I'm curious why it's implemented
> >differently here.

> The prepare  is called in atomic context and in this we are calling
> pm_runtime_get_sync() which is blocking and it can cause issue.

> I have already bug reported by you that sometimes you saw locking in
> tegra20 slink driver which we need to fix. When testing this, I ran
> into similar case and hence now moving this out or prepare.

> I will push the change for fixing this in tegra20_slink driver also.

As I think I've said before I keep thinking we ought to just have some
basic runtime PM code in the core - a substantial proportion of drivers
end up following the same pattern, it'd be surprising to see hardware
that needed a different pattern.

> >>+	tspi->clk = devm_clk_get(&pdev->dev, "spi");

> >Does this HW block use multiple clocks? If not, I think s/"spi"/NULL/
> >there, just like the Tegra20 driver.

> No, spi controller uses the only one clock. I will change to NULL.

I'm never convinced that NULL is a helpful clock name to pick, it's not
awesome if you ever acquire a second clock.

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