RE: [PATCH v2 0/7] Add the iMX8MP PCIe support

[Hongxing Zhu]

> -----Original Message-----
> From: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Sent: 2022年4月13日 15:22
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>; tharvey@xxxxxxxxxxxxx;
> Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> Cc: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>; bhelgaas@xxxxxxxxxx; Lorenzo
> Pieralisi <lorenzo.pieralisi@xxxxxxx>; Rob Herring <robh@xxxxxxxxxx>; Shawn
> Guo <shawnguo@xxxxxxxxxx>; Vinod Koul <vkoul@xxxxxxxxxx>;
> linux-phy@xxxxxxxxxxxxxxxxxxx; Device Tree Mailing List
> <devicetree@xxxxxxxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; Linux ARM Mailing
> List <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; open list
> <linux-kernel@xxxxxxxxxxxxxxx>; Sascha Hauer <kernel@xxxxxxxxxxxxxx>;
> dl-linux-imx <linux-imx@xxxxxxx>
> Subject: Re: [PATCH v2 0/7] Add the iMX8MP PCIe support
> 
> Hi Richard,
> 
> Am Montag, dem 11.04.2022 um 03:32 +0000 schrieb Hongxing Zhu:
> > > -----Original Message-----
> > > From: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> > > Sent: 2022年4月8日 16:13
> > > To: Hongxing Zhu <hongxing.zhu@xxxxxxx>; tharvey@xxxxxxxxxxxxx;
> > > Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > > Cc: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>; bhelgaas@xxxxxxxxxx;
> > > Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>; Rob Herring
> > > <robh@xxxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>; Vinod Koul
> > > <vkoul@xxxxxxxxxx>; linux-phy@xxxxxxxxxxxxxxxxxxx; Device Tree
> > > Mailing List <devicetree@xxxxxxxxxxxxxxx>;
> > > linux-pci@xxxxxxxxxxxxxxx; Linux ARM Mailing List
> > > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; open list
> > > <linux-kernel@xxxxxxxxxxxxxxx>; Sascha Hauer
> > > <kernel@xxxxxxxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>
> > > Subject: Re: [PATCH v2 0/7] Add the iMX8MP PCIe support
> > >
> > > Am Freitag, dem 08.04.2022 um 03:14 +0000 schrieb Hongxing Zhu:
> > > > >
> > > [...]
> > > > > Richard,
> > > > >
> > > > > Thanks for working on this!
> > > > >
> > > > > Do you plan on submitting another version soon? I've tried to
> > > > > test this with an imx8mp board I'm bringing up and while the
> > > > > host controller enumerates I fail to get a link to a device.
> > > > > It's very likely I am missing something as this series depends
> > > > > on the IMX8MP blk-ctrl
> > > and gpc series which I also can't cleanly apply.
> > > > > Lucas just submitted a 'consolidated i.MX8MP HSIO/MEDIA/HDMI
> > > > > blk-ctrl series' [1] yet I can't find a repo/branch that applies
> > > > > to either.
> > > > >
> > > > > Perhaps you have a git repo somewhere I can look at while we
> > > > > wait for imx8mp blk-ctl/gpc to settle and you to submit a v3?
> > > > Hi Tim:
> > > > Thanks for your kindly help to do the tests.
> > > > I had listed the dependencies in the cover-letter log.
> > > > Alexander and I used to test this series commits based on the
> > > > V5.17 kernel.
> > > >
> > > > Lucas had provided some review comments and suggestions about the
> > > > PLL bits
> > > >  manipulations of HSIOMIX in i.MX8MP PCIe PHY driver #3 of this
> > > > series.
> > > > And he suggested to let the HSIOMIX blk-ctrl make this PLL as a
> > > > real clock,
> > > >  and used by i.MX8MP PCIe PHY driver later.
> > > >
> > > > Although I have some confusions, it's better let's wating for the
> > > > blk-ctrl settle down and get clear discussion with Lucas later.
> > > > How do you think about that?
> > >
> > > Just to let you know my plans: I was quite busy with getting the
> > > i.MX8MP HDMI part to work. Now that this is at least in a state
> > > where it can collect some feedback from upstream I have some time to
> > > circle back to this topic. I can't commit to do it immediately, but
> > > I'll get around to looking at the PCIe series a bit more in-depth
> > > and apply my HSIO PLL suggestion to the blk-ctrl driver during the
> > > next week.
> >
> > Hi Lucas:
> > Thanks for your helpful reply.
> > I know that you're busy with the blk-ctrl settle down now, and had
> > explained to Tim.
> 
> Yesterday I tried to get this series working on my 8MP-EVK board, but was
> unsuccessful for now. The PCIe link does not come up. PCIe REF_CLK is present
> and PERST de-asserted. I'm not sure if this is due to a faulty EP device (I don't
> have another M.2 KeyE device around to check) or if this may be due to the old
> revision of my 8MP-EVK, as I'm still working with a RevA board. The schematic
> revision log doesn't show anything that would obviously influence PCIe
> operation, but I have also not found any schematics for RevA.
> 
> Do you know if there have been any PCIe related changes/fixes in the later EVK
> board revisions?
> 
Hi Lucas:
First of all, thanks a lot for your kindly help on this series.
I remember that there is one PCIe related HW rework used to support the NVME
 device when Rev A board is used.
Here is description of this rework and hope it's helpful.

Support High power consumption NVMe SSD
Current EVK has limitation to support high power consumption NVMe SSD, transient
 voltage drop is high, need to change R452 to 0ohm to solve this issue.
Rework Steps:
Change R452  to 470-75394 0ohm, 0402

BTW, R452 is placed just at the right side of the M.2 slot.

Best Regards
Richard Zhu

> For now I'll try to get this working on a custom i.MX8MP board, where I can
> use a different EP device. Maybe I'll have a bit more luck there.
> 
> Regards,
> Lucas