Re: [PATCH RFC v4.14] PCI: aadrvark: warm reset the cores and card

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Lorenzo,

Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> wrote on Mon, 19 Nov 2018
17:09:48 +0000:

> On Wed, Oct 24, 2018 at 05:20:56PM +0200, Marek Behún wrote:
> > Add code to do a warm reset on the PHY and PCIE cores and if PERSTN GPIO
> > is specified in device tree (as reset-gpio), also reset the card.
> > 
> > The reset-gpio is inspired by what is done in U-Boot and linux-marvell,
> > and is not final version: I am hoping this can be done via a PCIe register
> > rather than GPIO - bit 3 of CTRL_WARM_RESET_REG register (which is added
> > by this patch) is called PERSTN_GPIO_EN (Enable PERSTN from GPIO) and
> > I think this is the right register, but manipulating this register did
> > not have any effect on the PERSTN pin, even when pinctrl was correctly set.
> > 
> > I asked Marvell about this and am awaiting their reply.
> > 
> > The reset-gpio is needed for Compex 5 GHz wifi card model WLE900VX. Without
> > this patch the PCIe link never comes up in kernel (although U-Boot pci
> > command was able to enumerate the card).
> > 
> > What is weird is that the link does not come up for this card when
> > pci-aardvark driver is probed in U-Boot. I haven't yet had time to discover
> > the problem there. My temporary solution is to compile out the pci-aardvark
> > driver from U-Boot.
> > 
> > This patch is based on 4.14 kernel.  
> 
> This is not a commit log, these comments go either in a cover letter
> or below the log, prior to the diff.
> 
> Patches should always be aimed at mainline, that's what is discussed
> and merged on linux-pci@vger.kernel.org
> 
> Given its RFC status I consider this patch a proof of concept and
> won't consider it for upstreaming, not yet at least.
> 
> > If you have time, please try it with some PCIe cards and let me know
> > if they work correctly.  
> 
> See above. For the time being I will drop this patch from the linux-pci
> patch queue, I really do not know what to do with it.
> 
> Thanks,
> Lorenzo

Just an FYI, I am currently working on S2RAM support on A3700, and
doing this I added a few things to this driver including reset GPIO
support. Patches will come soon. There is no warm-reset coming in
though. 

Thanks,
Miquèl