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Date: Mon, 3 Feb 2020 13:21:24 -0800 From: Florian Fainelli <florian.fainelli@...adcom.com> To: Stefan Wahren <wahrenst@....net>, Nicolas Saenz Julienne <nsaenzjulienne@...e.de>, Jeremy Linton <jeremy.linton@....com>, netdev@...r.kernel.org Cc: opendmb@...il.com, f.fainelli@...il.com, davem@...emloft.net, bcm-kernel-feedback-list@...adcom.com, linux-kernel@...r.kernel.org, andrew@...n.ch, hkallweit1@...il.com Subject: Re: [PATCH 6/6] net: bcmgenet: reduce severity of missing clock warnings On 2/3/20 11:08 AM, Stefan Wahren wrote: > Hi, > > Am 03.02.20 um 19:36 schrieb Nicolas Saenz Julienne: >> Hi, >> BTW the patch looks good to me too: >> >> Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de> >> >> On Sat, 2020-02-01 at 13:27 -0600, Jeremy Linton wrote: >>> Hi, >>> >>> First, thanks for looking at this! >>> >>> On 2/1/20 10:44 AM, Stefan Wahren wrote: >>>> Hi Jeremy, >>>> >>>> [add Nicolas as BCM2835 maintainer] >>>> >>>> Am 01.02.20 um 08:46 schrieb Jeremy Linton: >>>>> If one types "failed to get enet clock" or similar into google >>>>> there are ~370k hits. The vast majority are people debugging >>>>> problems unrelated to this adapter, or bragging about their >>>>> rpi's. Given that its not a fatal situation with common DT based >>>>> systems, lets reduce the severity so people aren't seeing failure >>>>> messages in everyday operation. >>>>> >>>> i'm fine with your patch, since the clocks are optional according to the >>>> binding. But instead of hiding of those warning, it would be better to >>>> fix the root cause (missing clocks). Unfortunately i don't have the >>>> necessary documentation, just some answers from the RPi guys. >>> The DT case just added to my ammunition here :) >>> >>> But really, I'm fixing an ACPI problem because the ACPI power management >>> methods are also responsible for managing the clocks. Which means if I >>> don't lower the severity (or otherwise tweak the code path) these errors >>> are going to happen on every ACPI boot. >>> >>>> This is what i got so far: >> Stefan, Apart from the lack of documentation (and maybe also time), is there >> any specific reason you didn't sent the genet clock patch yet? It should be OK >> functionally isn't it? > > last time i tried to specify the both clocks as suggest by the binding > document (took genet125 for wol, not sure this is correct), but this > caused an abort on the BCM2711. In the lack of documentation i stopped > further investigations. As i saw that Jeremy send this patch, i wanted > to share my current results and retestet it with this version which > doesn't crash. I don't know the reason why both clocks should be > specified, but this patch should be acceptable since the RPi 4 doesn't > support wake on LAN. Your clock changes look correct, but there is also a CLKGEN register block which has separate clocks for the GENET controller, which lives at register offset 0x7d5e0048 and which has the following layout: bit 0: GENET_CLK_250_CLOCK_ENABLE bit 1: GENET_EEE_CLOCK_ENABLE bit 2: GENET_GISB_CLOCK_ENABLE bit 3: GENET_GMII_CLOCK_ENABLE bit 4: GENET_HFB_CLOCK_ENABLE bit 5: GENET_L2_INTR_CLOCK_ENABLE bit 6: GENET_SCB_CLOCK_ENABLE bit 7: GENET_UNIMAC_SYS_RX_CLOCK_ENABLE bit 8: GENET_UNIMAC_SYS_TX_CLOCK_ENABLE you will need all of those clocks turned on for normal operation minus EEE, unless EEE is desirable which is why it is a separate clock. Those clocks default to ON unless turned off, and the main gate that you control is probably enough. The Pi4 could support Wake-on-LAN with appropriate VPU firmware changes, but I do not believe there is any interest in doing that. I would not "bend" the clock representation just so as to please the driver with its clocking needs. -- Florian
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