Date: Thu, 8 Oct 2020 13:34:12 -0500 From: Kyle Evans <kevans@freebsd.org> Cc: Mark Millard <marklmi@yahoo.com>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: RPi4B: emmc2bus dma-range handling does not track the boot-time-FDT (u-boot based booting) Message-ID: <CACNAnaFXpJcA5Xyw%2BPR6iem3U2nvpog53hsnCFKiGWiO6OgKKA@mail.gmail.com> In-Reply-To: <CACNAnaEZP=Gxs4cbvCOFzM8MZB6-2Ny0N7KEW-nYoDw22_Jzwg@mail.gmail.com> References: <D8BDF95A-D6A8-4E95-A0CE-D53068E8355B.ref@yahoo.com> <D8BDF95A-D6A8-4E95-A0CE-D53068E8355B@yahoo.com> <CACNAnaG3CKTiXdXNUO1Jgr34=XGF4wYRuUnuiJRhNb1J9XaGbw@mail.gmail.com> <CACNAnaEZP=Gxs4cbvCOFzM8MZB6-2Ny0N7KEW-nYoDw22_Jzwg@mail.gmail.com>
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On Thu, Oct 8, 2020 at 12:38 PM Kyle Evans <kevans@freebsd.org> wrote: > > On Thu, Oct 8, 2020 at 11:33 AM Kyle Evans <kevans@freebsd.org> wrote: > > > > On Thu, Oct 8, 2020 at 4:01 AM Mark Millard via freebsd-arm > > <freebsd-arm@freebsd.org> wrote: > > > > > > sys/gnu/dts/arm/bcm2711.dtsi reports: > > > > > > /* > > > * emmc2 has different DMA constraints based on SoC revisions. It was > > > * moved into its own bus, so as for RPi4's firmware to update them. > > > * The firmware will find whether the emmc2bus alias is defined, and if > > > * so, it'll edit the dma-ranges property below accordingly. > > > */ > > > [... snip ...] > > > > I have no words for how annoying this is. > > > > For a slightly more helpful response: > > We can fix this, and it ends up being much cleaner than my current > hack. Basically, in bcm2835_vcbus.c, we should eradicate the > busdma_lowaddr from bcm283x_memory_soc_cfg. > > bcm283x_dmabus_peripheral_lowaddr should instead take a device_t and > grab the bus's dma-ranges. It /looks/ to be valid on all the DTS I see > for the RPi boards we support, so we can just unconditionally use that > and things will just work for the newer RPi4 models. > > From my discussion (with an assist Ian on address interpretation) on > IRC, so I don't forget: > > dma-ranges is three-value: <dma_addr cpu_addr max_len> > > We'll see 4 and 5 value variants of this because 64-bit addresses are > described with pairs of 32-bit values. > > 4-value variant: dma_addr will be 32-bit, cpu_addr will be 64-bit > 5-value variant: both are 64-bit > > Note that bcm283x_dmabus_peripheral_lowaddr() will be returning > cpu_addr + (max_len - 1) > > This won't match perfectly with what we currently return, but it will > be more accurate. Here's a patch that I hacked out and can't test for quite a while yet, feel free to give it a shot: https://people.freebsd.org/~kevans/bcm2835_vcbus.diff -- the best guarantee I can give you is that it builds. We'll need to test it on both RPi4 models with the separate bus and the original RPi4s, as well as an RPi3 and RPi2/0w. Thanks, Kyle Evans
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