Messages in this thread | | | From | Rajan Vaja <> | Subject | RE: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface | Date | Fri, 31 Jan 2020 09:05:15 +0000 |
| |
Hi Greg,
> -----Original Message----- > From: Greg KH <gregkh@linuxfoundation.org> > Sent: 31 January 2020 11:41 AM > To: Jolly Shah <JOLLYS@xilinx.com> > Cc: ard.biesheuvel@linaro.org; mingo@kernel.org; matt@codeblueprint.co.uk; > sudeep.holla@arm.com; hkallweit1@gmail.com; keescook@chromium.org; > dmitry.torokhov@gmail.com; Michal Simek <michals@xilinx.com>; Rajan Vaja > <RAJANV@xilinx.com>; linux-arm-kernel@lists.infradead.org; linux- > kernel@vger.kernel.org > Subject: Re: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface > > EXTERNAL EMAIL > > 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 :) [Rajan] Sorry for multiple back and forth but as I understand, you are suggesting to create a new API for Read/write of GGS register instead of using PM_IOCTL API (eemi_ops->ioctl) for multiple purpose. Is my understanding correct?
Thanks, Rajan
> > thanks, > > greg k-h
| |