On 1/3/2023 2:46 PM, Hector Martin wrote:
On 03/01/2023 22.30, Arend van Spriel wrote:On 1/3/2023 4:55 AM, Hector Martin wrote:On 2023/01/03 3:27, Arend Van Spriel wrote:On January 2, 2023 4:15:41 PM Hector Martin <marcan@xxxxxxxxx> wrote:On 02/01/2023 23.40, Aditya Garg wrote:From: Aditya Garg <gargaditya08@xxxxxxxx> Commit 'dce45ded7619' added support for 89459 chip pcie device. It uses the BRCM4355 chip which is also found in Apple hardware. However this commit causes conflicts in the firmware naming between Apple hardware, which supports OTP and other non-Apple hardwares. So, this patch makes these Apple chips use their own firmware table so as to avoid possible conflicts like these in the future.I think my reply to Arend flew over your head. My point was that I'd rather have the Broadcom/Cypress people actually answer my question so we can figure out how to do this *properly*, instead of doing "safer-but-dumb" things (like this patch) because we just don't have the information to do it properly.Fair enough. Can you accurately (re)state your question and I will try to answer it.As per my original email: Is the CYW89459 just a rebrand of the BCM4355, or just a subset? Can we consider them equivalent, and equivalent to the Apple part (BCM4355C1 / revision 12)?There is probably no easy answer. Mainly because Cypress is a separate entity. However, they use the same/similar technology and code base. So let me first start with the chip naming. The wifi chip primarily has a number and revision. The chip number is straighforward and can be read from the device. The chip revision comes in two variants: 1) simple increasing number as read from the device, and 2) a <letter><digit> format. The latter start at a0, which you almost never see in the wild unless we do it "first time right". Whenever spinning a new chip we either increase the digit or the letter depending on type/amount of changes. There is not predictable mapping between the revision variants. Depending on the hurdles in a chip project we may move from a0 to b0, or from b0 to b1 or whatever.Right, this is standard chip spin numbering, that much I know.If CYW89459 chip reads chip number 0x4355 than it is a BCM4355. If it is a different revision it may require different firmware. A different letter will always require different firmware. A different digit may work although the firmware can have code paths for a specific revision.So is it always correct to have the same firmware (in a generic situation, not a customized OEM build) for, say, a BCM4355 rev 12, regardless of what the PCI ID programmed into the OTP is (and what the marketing device name is)?
Yes.
If so, then my conclusion is that the original patch I replied to is incorrect, all the defines should've been called BCM4355 (not the Cypress part number), and we probably need two firmware table entries since (judging by the revision check elsewhere in that patch) there are other revisions in the wild than the one Apple uses, and therefore there should at the very least be a firmware name split at C1. It would then be very helpful to know what revisions *do* exist and their correct naming.
I can only track down what we have in Broadcom. For the 4355 the revisions B1 (=6), B3 (=8), C0 (=10) and C1 are mentioned as released. Here things get weird, because you mentioned BCM4355 rev12, which would be a C2. So without asking around I can only assume this C2 variant is not different from firmware perspective and can happily run the C1 firmware.
If different PCI device IDs might need different firmware, then the exiting firmware selection/table mechanism is insufficient.Happy New year to you. Thanks for clearly marking the rant. Makes it easier to ignore, but let me get into this. I would not call bcmdhd the downstream driver. It is a separate out-of-tree driver. Indeed resources were pulled from brcm80211 development, but there always have been only 2 or 3 people working on it. Me being the constant working mule and these days only for 20% of my working hours to do the job. So you are not really doing our job as we are not assigned to do so. I guess there is no ROI for Broadcom or so it is perceived and there is no customer pushing for it. That said I am always happy to help and clarify whatever I can.Is there any chance you can provide a list of chips/shipping revisions and revision IDs, so we can stop guessing at the mappings in the firmware table? Because this is effectively breaking userspace ABI every time we make a change to an existing chip, as it can change the firmware file name that userspace loads. This already happened with BCM4364, where (at least) B2 and B3 revisions exist in the wild and we need separate firmwares, yet it was added with a full mask, resulting in people copying "the right firmware for them" manually and my patch to split it into properly named firmwares will break those users.
Userspace is not loading anything these days. AFAIK the kernel is directly accessing the firmware file. Anyway, I never considered this as being a big issue. If people change their installed os to get things working, they can expect the reverse can happen anytime and deal with it once more. If this is considered a real issue we should only set the revmask for the revision we know to be working.
Regards, Arend
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