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Mon, 23 Mar 2026 13:23:28 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AJPKs3BxgghB Date: Mon, 23 Mar 2026 13:23:07 -0400 From: "Mark Pearson" To: "Manivannan Sadhasivam" , "Dmitry Baryshkov" Cc: "Rob Herring" , "Manivannan Sadhasivam" , "Greg KH" , "Jiri Slaby" , "Nathan Chancellor" , "Nicolas Schier" , "Hans de Goede" , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , "Derek J . Clark" , "Krzysztof Kozlowski" , "Conor Dooley" , "Marcel Holtmann" , "Luiz Augusto von Dentz" , "Bartosz Golaszewski" , "Andy Shevchenko" , "Bartosz Golaszewski" , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, "platform-driver-x86@vger.kernel.org" , linux-pci@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-bluetooth@vger.kernel.org, linux-pm@vger.kernel.org, "Stephan Gerhold" , "linux-acpi@vger.kernel.org" Message-Id: <3faffec9-dc9d-4eec-a652-a84d30d85c96@app.fastmail.com> In-Reply-To: References: <20260317-pci-m2-e-v6-0-9c898f108d3d@oss.qualcomm.com> <20260317-pci-m2-e-v6-6-9c898f108d3d@oss.qualcomm.com> <20260322233713.GA98177-robh@kernel.org> <6aef3xxjjd4nbgrfx6jc6jt6rpqmttoui6hil5zqgdpas2j6gj@ie6j72orenou> Subject: Re: [PATCH v6 6/9] dt-bindings: connector: m2: Add M.2 1620 LGA soldered down connector Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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 w= rote: >> > > > On Mon, Mar 23, 2026 at 08:39:55AM -0500, Rob Herring wrote: >> > > > > On Mon, Mar 23, 2026 at 7:16=E2=80=AFAM Manivannan Sadhasivam= 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 Sadh= asivam wrote: >> > > > > > > > Lenovo Thinkpad T14s is found to have a soldered down v= ersion 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 innovat= ive as possible to >> > > > > > save the BOM cost. >> > > > >=20 >> > > > > innovation =3D=3D incompatible changes >> > > > >=20 >> > > >=20 >> > > > Yes, I was trying to sound nice :) >> > > >=20 >> > > > > > This is why I do not want to make it Lenovo specific. But i= f you prefer that, I >> > > > > > can name it as "lenovo,pcie-m2-1620-lga-connector". >> > > > >=20 >> > > > > Depends if you think that s/w needs to know the differences. = Hard to >> > > > > say with a sample size of 1. >> > > > >=20 >> > > >=20 >> > > > Sure. Will add the 'lenovo' prefix then. >> > >=20 >> > > Is it really Lenovo? Or is it some other module vendor, whose LGA= s are >> > > being used by Lenovo? >> > >=20 >> > > I remember that DB820c also used some kind of a module for the Wi= Fi card >> > > (which might be M.2 compatible or might not, I can't find exact d= ocs at >> > > this point). >> > >=20 >> >=20 >> > I don't know. These kind of designs might be reused by several vend= ors. 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. >>=20 >> ... 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".=20 >>=20 > > How do you possibly know whether a single vendor has introduced this f= orm factor > or reused by multiple ones? Atleast, I don't have access to such a sou= rce 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 specif= ically 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 hol= d up the review for a bit and I may not be able to get a straight answer) My vote (for what little it's worth) would be to make it non-Lenovo spec= ific. Then when the same part causes issues on another vendors platform = I won't get asked questions about why Lenovo is breaking = :) Mark