linux-kernel - Re: [PATCH 1/3] amba: add no_pm_pclk_management flag to amba

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] [day] [month] [year] [list]

Date:	Tue, 05 May 2015 08:21:50 +0200
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	dan.j.williams@...el.com, vinod.koul@...el.com, lars@...afoo.de,
	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
	m.szyprowski@...sung.com
Subject: Re: [PATCH 1/3] amba: add no_pm_pclk_management flag to amba_driver

On 04/16/2015 03:41 PM, Russell King - ARM Linux wrote:
> On Thu, Apr 16, 2015 at 03:39:12PM +0200, Robert Baldyga wrote:
>> This patch introduces no_pm_pclk_management flag in struct amba_driver.
>> It causes that pclk is not touched in pm_runtime callbacks. This allows
>> to manage clock in device driver independently of power domain management.
> 
> NAK.  We already have stuff in place to deal with the problem with
> DMA engine using runtime PM, which causes pclk management to fall
> back to the IRQ-safe clk_enable/clk_disable().
> 

What kind of stuff do you mean? If we want to manage pclk independently
form runtime PM, we need to prevent AMBA driver from touching pclk.
Otherwise our clock management inside of dmaengine driver is ineffective
because pclk refcount is incremented by AMBA driver.

Thanks,
Robert Baldyga
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/