linux-kernel - Re: [PATCH v2 0/2] drivers: provide devm_platform_request

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]
Message-ID: <20200527134726.GD7143@nuc8i5>
Date:   Wed, 27 May 2020 21:47:26 +0800
From:   Dejin Zheng <zhengdejin5@...il.com>
To:     Grygorii Strashko <grygorii.strashko@...com>
Cc:     Michal Simek <michal.simek@...inx.com>,
        Wolfram Sang <wsa@...nel.org>, gregkh@...uxfoundation.org,
        linus.walleij@...aro.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] drivers: provide devm_platform_request_irq()

On Tue, May 26, 2020 at 08:13:25PM +0300, Grygorii Strashko wrote:
> 
> 
> On 25/05/2020 10:05, Michal Simek wrote:
> > On 23. 05. 20 19:09, Dejin Zheng wrote:
> > > On Sat, May 23, 2020 at 06:08:29PM +0200, Wolfram Sang wrote:
> > > > On Sat, May 23, 2020 at 10:51:55PM +0800, Dejin Zheng wrote:
> > > > > It will call devm_request_irq() after platform_get_irq() function
> > > > > in many drivers, sometimes, it is not right for the error handling
> > > > > of these two functions in some drivers. so provide this function
> > > > > to simplify the driver.
> > > > > 
> > > > > the first patch will provide devm_platform_request_irq(), and the
> > > > > other patch will convert to devm_platform_request_irq() in some
> > > > > i2c bus dirver.
> > > > > 
> > > > > v1 -> v2:
> > > > > 	- I give up this series of patches in v1 version. I resend this
> > > > > 	  patches v2 by that discussion:
> > > > > 	  https://patchwork.ozlabs.org/project/linux-i2c/patch/20200520144821.8069-1-zhengdejin5@gmail.com/
> > > > > 	  The patch content has not changed.
> > > > 
> > > > I don't understand. v1 has been nacked because of technical reasons. How
> > > > did the discussion above change the situation? Am I missing something?
> > > > 
> > > No, you are not missing something. Maybe I did not explain clearly.
> > > 
> > > The v1 has been nacked because Grygorii told me that the
> > > function platform_get_irq() should be done as early as possible to avoid
> > > unnecessary initialization steps, and the function devm_request_irq()
> > > should be done late in probe when driver and HW are actually ready to
> > > handle IRQs. It can do the other things between the two funtions. I agree
> > > with him that it may be necessary in some complex drives. So abandon the
> > > patch v1.
> > > 
> > > Base on the discussion of you and Michal, I think maybe this patch is also
> > > needed for the simple driver or the driver of already use it like that:
> > > 	
> > > 	irq = platform_get_irq(pdev, 0);
> > > 	if (irq < 0)
> > > 		return irq;
> > > 	ret = devm_request_irq()
> > > 
> > > It provides a common error handling and reduce one function call for each
> > > drivers, more easier to use and simplify code. So resend it.
> > > 
> > > BR,
> > > Dejin
> > > 
> > > > > 
> > > > > Dejin Zheng (2):
> > > > >    drivers: provide devm_platform_request_irq()
> > > > >    i2c: busses: convert to devm_platform_request_irq()
> > > > > 
> > > > >   drivers/base/platform.c            | 33 ++++++++++++++++++++++++++++++
> > > > >   drivers/i2c/busses/i2c-bcm-kona.c  | 16 +++------------
> > > > >   drivers/i2c/busses/i2c-cadence.c   | 10 +++------
> > > > >   drivers/i2c/busses/i2c-digicolor.c | 10 +++------
> > > > >   drivers/i2c/busses/i2c-emev2.c     |  5 ++---
> > > > >   drivers/i2c/busses/i2c-jz4780.c    |  5 ++---
> > > > >   drivers/i2c/busses/i2c-meson.c     | 13 ++++--------
> > > > >   drivers/i2c/busses/i2c-mxs.c       |  9 +++-----
> > > > >   drivers/i2c/busses/i2c-pnx.c       |  9 ++------
> > > > >   drivers/i2c/busses/i2c-rcar.c      |  9 +++-----
> > > > >   drivers/i2c/busses/i2c-rk3x.c      | 14 +++----------
> > > > >   drivers/i2c/busses/i2c-sirf.c      | 10 ++-------
> > > > >   drivers/i2c/busses/i2c-stu300.c    |  4 ++--
> > > > >   drivers/i2c/busses/i2c-synquacer.c | 12 +++--------
> > > > >   include/linux/platform_device.h    |  4 ++++
> > > > >   15 files changed, 72 insertions(+), 91 deletions(-)
> > 
> > If you look at all driver except for cadence one it doesn't do any
> > change and I can't see any issue with it because sequences are the same
> > as were before.
> > 
> > Regarding Cadence and Grygorii's comments:
> > We are not checking that id->irq is valid that's why even if that fails
> > driver continues to work. Which means that this change doesn't increase
> > boot time or change code flow.
> > On Xilinx devices cadence i2c is connected to ARM GIC which is
> > initialized very early and IRC controller should be up and running all
> > the time.
> > That's why I can't see any issue which this change on Cadence driver too.
> 
> 
> My main point was to pay attention on changes, which may be risky
> especially when they are part of bulk changes (such optimization tend to spread
> fast and all over the kernel without proper review).
> 
> Sry, if i introduced some misunderstanding, but it seems worked and this patch has got more attention.
> There are no objection from my side to use devm_platform_get_and_ioremap_resource() if driver
> owners find it acceptable.
>
This should be my misunderstanding regarding your comment in patch v1,
Anyway, thanks everyone for using your precious time to review my patch.

And also I very sorry for the Gmail will prevent me sending messages to
a large number of recipient, I had to reduce the number of recipients to
send this email. so sorry!

BR,
Dejin

> -- 
> Best regards,
> grygorii