Re: [PATCH v6 6/9] dt-bindings: connector: m2: Add M.2 1620 LGA soldered down connector

[Dmitry Baryshkov]

On Wed, Jun 10, 2026 at 06:44:59PM +0200, Manivannan Sadhasivam wrote:
> On Tue, Mar 31, 2026 at 06:29:51PM +0200, Stephan Gerhold wrote:
> > On Wed, Mar 25, 2026 at 05:36:08PM +0530, Manivannan Sadhasivam wrote:
> > > On Mon, Mar 23, 2026 at 01:23:07PM -0400, Mark Pearson wrote:
> > > > On Mon, Mar 23, 2026, at 12:52 PM, Manivannan Sadhasivam wrote:
> > > > > On Mon, Mar 23, 2026 at 06:45:15PM +0200, Dmitry Baryshkov wrote:
> > > > >> On Mon, Mar 23, 2026 at 09:26:04PM +0530, Manivannan Sadhasivam wrote:
> > > > >> > On Mon, Mar 23, 2026 at 05:14:30PM +0200, Dmitry Baryshkov wrote:
> > > > >> > > On Mon, Mar 23, 2026 at 07:14:25PM +0530, Manivannan Sadhasivam wrote:
> > > > >> > > > On Mon, Mar 23, 2026 at 08:39:55AM -0500, Rob Herring wrote:
> > > > >> > > > > On Mon, Mar 23, 2026 at 7:16 AM Manivannan Sadhasivam <mani@xxxxxxxxxx> wrote:
> > > > >> > > > > >
> > > > >> > > > > > On Sun, Mar 22, 2026 at 06:37:13PM -0500, Rob Herring wrote:
> > > > >> > > > > > > On Tue, Mar 17, 2026 at 09:59:56AM +0530, Manivannan Sadhasivam wrote:
> > > > >> > > > > > > > Lenovo Thinkpad T14s is found to have a soldered down version of M.2 1620
> > > > >> > > > > > > > LGA connector. Though, there is no 1620 LGA form factor defined in the M.2
> > > > >> > > > > > > > spec, it looks very similar to the M.2 Key E connector. So add the
> > > > >> > > > > > > > "pcie-m2-1620-lga-connector" compatible with "pcie-m2-e-connector" fallback
> > > > >> > > > > > > > to reuse the Key E binding.
> > > > >> > > > > > >
> > > > >> > > > > > > What is LGA?
> > > > >> > > > > > >
> > > > >> > > > > >
> > > > >> > > > > > Land Grid Array
> > > > >> > > > > >
> > > > >> > > > > > > If not in the spec, is it really something generic?
> > > > >> > > > > > >
> > > > >> > > > > >
> > > > >> > > > > > Good question. Yes and No! LGA is not something that Lenovo only uses. Other
> > > > >> > > > > > vendors may also use this form factor. PCIe connectors are full of innovation as
> > > > >> > > > > > the spec gives room for hardware designers to be as innovative as possible to
> > > > >> > > > > > save the BOM cost.
> > > > >> > > > > 
> > > > >> > > > > innovation == incompatible changes
> > > > >> > > > > 
> > > > >> > > > 
> > > > >> > > > Yes, I was trying to sound nice :)
> > > > >> > > > 
> > > > >> > > > > > This is why I do not want to make it Lenovo specific. But if you prefer that, I
> > > > >> > > > > > can name it as "lenovo,pcie-m2-1620-lga-connector".
> > > > >> > > > > 
> > > > >> > > > > Depends if you think that s/w needs to know the differences. Hard to
> > > > >> > > > > say with a sample size of 1.
> > > > >> > > > > 
> > > > >> > > > 
> > > > >> > > > Sure. Will add the 'lenovo' prefix then.
> > > > >> > > 
> > > > >> > > Is it really Lenovo? Or is it some other module vendor, whose LGAs are
> > > > >> > > being used by Lenovo?
> > > > >> > > 
> > > > >> > > I remember that DB820c also used some kind of a module for the WiFi card
> > > > >> > > (which might be M.2 compatible or might not, I can't find exact docs at
> > > > >> > > this point).
> > > > >> > > 
> > > > >> > 
> > > > >> > I don't know. These kind of designs might be reused by several vendors. But
> > > > >> > considering that we should not make it generic, I'd go with Lenovo as that's
> > > > >> > the only vendor we know as of now.
> > > > >> 
> > > > >> ... and later we learn that other vendors use the same idea /pinout,
> > > > >> then nothing stops us from still telling that it's a
> > > > >> "lenovo,pcie-m2-something-lga". 
> > > > >> 
> > > > >
> > > > > How do you possibly know whether a single vendor has introduced this form factor
> > > > > or reused by multiple ones? Atleast, I don't have access to such a source to
> > > > > confirm.
> > > > >
> > > > I've not really been following this thread/patchset in detail; but want me to try and check with the T14s platform team if this device is specifically made for us (Lenovo) or not?
> > > > I doubt it is - we just don't do that usually, but I can go and ask the question if it will help resolve this (with the caveat that it could hold up the review for a bit and I may not be able to get a straight answer)
> > > > 
> > > 
> > > I can drop this specific patch in the meantime.
> > > 
> > > > My vote (for what little it's worth) would be to make it non-Lenovo specific. Then when the same part causes issues on another vendors platform I won't get asked questions about why Lenovo is breaking <other vendor> :)
> > > > 
> > > 
> > > Even if Lenovo prefix is used, it won't break other vendors. Just that we will
> > > end up adding more compatibles.
> > > 
> > > Anyhow, I'll wait for your reply and drop this patch for next revision.
> > > 
> > 
> > If you need a vendor prefix, I think "qcom," would be more appropriate
> > than Lenovo. This form factor is used by most vendors for recent
> > soldered Qualcomm-based wireless cards, not just Lenovo:
> > 
> >  - Dell XPS 13 9345 has exactly the same soldered M.2 card, I assume
> >    there are several other vendors as well.
> > 
> >  - https://www.sparklan.com/product/wnsq-290be/ is a third-party
> >    (Qualcomm-based) M.2 LGA 1620 card, in the block diagram the
> >    pinout is called "QM.2 1620 LGA 168pin".
> > 
> >  - If you press F9 while booting the ThinkPad T14s, you should get to a
> >    screen with "Regulatory Information". For the T14s, this screen says
> >    "Contains FCC ID: J9C-QCNCM825". This is the WiFi/BT module in the
> >    soldered form factor. If you look that up on the FCC website, the
> >    applicant for this module is "Qualcomm Technologies, Inc.". This
> >    seems to be some kind of "modular certification" that vendors can
> >    reuse/adapt without going through the whole process again.
> > 
> > Perhaps you should ask around inside Qualcomm? :-)
> > 
> 
> Sorry for getting back after this long. I did ask around, but our HW folks are
> saying that Qcom is not the first one to use LGA M.2 modules. They claim that
> other vendors also do that.

I think, the idea was that there is no single standard for LGA modules
(please correct me if I'm wrong, I haven't checked the latest PCIe
standards).

> 
> But for this specific card, it should be fine to use the 'qcom' prefix as
> apparently the module was supplied by Qcom.
> 
> I'll submit the bindings patch together with DTS change for T14s.
> 
> - Mani
> 
> -- 
> மணிவண்ணன் சதாசிவம்

-- 
With best wishes
Dmitry