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From: Greg KH <gregkh@linuxfoundation.org>
To: Jolly Shah <JOLLYS@xilinx.com>
Cc: "ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
	"mingo@kernel.org" <mingo@kernel.org>,
	"matt@codeblueprint.co.uk" <matt@codeblueprint.co.uk>,
	"sudeep.holla@arm.com" <sudeep.holla@arm.com>,
	"hkallweit1@gmail.com" <hkallweit1@gmail.com>,
	"keescook@chromium.org" <keescook@chromium.org>,
	"dmitry.torokhov@gmail.com" <dmitry.torokhov@gmail.com>,
	Michal Simek <michals@xilinx.com>, Rajan Vaja <RAJANV@xilinx.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface
Date: Fri, 31 Jan 2020 07:10:38 +0100	[thread overview]
Message-ID: <20200131061038.GA2180358@kroah.com> (raw)
In-Reply-To: <4EF659A1-2844-46B9-9ED6-5A6A20401D9D@xilinx.com>

On Thu, Jan 30, 2020 at 11:59:03PM +0000, Jolly Shah wrote:
> Hi Greg,
> 
> On 1/27/20, 10:28 PM, "linux-kernel-owner@vger.kernel.org on behalf of Greg KH" <linux-kernel-owner@vger.kernel.org on behalf of gregkh@linuxfoundation.org> wrote:
> 
>     On Mon, Jan 27, 2020 at 11:01:27PM +0000, Jolly Shah wrote:
>     >     > > > +	ret = kstrtol(tok, 16, &value);
>     >     > > > +	if (ret) {
>     >     > > > +		ret = -EFAULT;
>     >     > > > +		goto err;
>     >     > > > +	}
>     >     > > > +
>     >     > > > +	ret = eemi_ops->ioctl(0, read_ioctl, reg, 0, ret_payload);
>     >     > > 
>     >     > > This feels "tricky", if you tie this to the device you have your driver
>     >     > > bound to, will this make it easier instead of having to go through the
>     >     > > ioctl callback?
>     >     > > 
>     >     > 
>     >     > GGS(general global storage) registers are in PMU space and linux doesn't have access to it 
>     >     > Hence ioctl is used.
>     >     
>     >     Why not just a "real" call to the driver to make this type of reading?
>     >     You don't have ioctls within the kernel for other drivers to call,
>     >     that's not needed at all.
>     > 
>     > these registers are for users  and for special needs where users wants
>     > to retain values over resets. but as they belong to PMU address space,
>     > these interface APIs are provided. They don’t allow access to any
>     > other registers.
>     
>     That's not the issue here.  The issue is you are using an "internal"
>     ioctl, instead just make a "real" call.
> 
> Sorry I am not clear. Do you mean that we should use linux standard
> ioctl interface instead of internal ioctl by mentioning "real" ?

No, you should just make a "real" function call to the exact thing you
want to do.  Not have an internal multi-plexor ioctl() call that others
then call.  This isn't a microkernel :)

thanks,

greg k-h

  reply	other threads:[~2020-01-31  6:10 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-08 23:54 [PATCH v2 0/4] firmware: xilinx: Add xilinx specific sysfs interface Jolly Shah
2020-01-08 23:54 ` [PATCH v2 1/4] firmware: xilinx: Add " Jolly Shah
2020-01-14 14:52   ` Greg KH
2020-01-23 23:47     ` Jolly Shah
2020-01-24  6:03       ` Greg KH
2020-01-24 11:32         ` Sudeep Holla
2020-01-27 22:46           ` Jolly Shah
2020-01-27 23:01         ` Jolly Shah
2020-01-28  6:28           ` Greg KH
2020-01-30 23:59             ` Jolly Shah
2020-01-31  6:10               ` Greg KH [this message]
2020-01-31  9:05                 ` Rajan Vaja
2020-01-31  9:36                   ` 'Greg KH'
2020-02-11  0:57                     ` Jolly Shah
2020-02-14 17:10                       ` 'Greg KH'
2020-02-15  0:37                         ` Jolly Shah
2020-02-15  0:52                           ` 'Greg KH'
2020-02-19 22:50                             ` Jolly Shah
2020-03-06 23:55                             ` Jolly Shah
2020-03-07  8:47                               ` 'Greg KH'
2020-01-08 23:54 ` [PATCH v2 2/4] firmware: xilinx: Add system shutdown API interface Jolly Shah
2020-01-08 23:54 ` [PATCH v2 3/4] firmware: xilinx: Add sysfs to set shutdown scope Jolly Shah
2020-01-08 23:54 ` [PATCH v2 4/4] firmware: xilinx: Add sysfs and IOCTL to set boot health status Jolly Shah

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