Re: [PATCH 2/2] arm64: dts: marvell: armada-37xx: Extend PCIe MEM space

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Fri, Jul 23, 2021 at 04:12:04PM +0200, Pali Rohár wrote:
> On Friday 23 July 2021 14:52:25 Gregory CLEMENT wrote:
> > Hello Pali,
> > 
> > > Current PCIe MEM space of size 16 MB is not enough for some combination
> > > of PCIe cards (e.g. NVMe disk together with ath11k wifi card). ARM Trusted
> > > Firmware for Armada 3700 platform already assigns 128 MB for PCIe window,
> > > so extend PCIe MEM space to the end of 128 MB PCIe window which allows to
> > > allocate more PCIe BARs for more PCIe cards.
> > >
> > > Without this change some combination of PCIe cards cannot be used and
> > > kernel show error messages in dmesg during initialization:
> > >
> > >     pci 0000:00:00.0: BAR 8: no space for [mem size 0x01800000]
> > >     pci 0000:00:00.0: BAR 8: failed to assign [mem size 0x01800000]
> > >     pci 0000:00:00.0: BAR 6: assigned [mem 0xe8000000-0xe80007ff pref]
> > >     pci 0000:01:00.0: BAR 8: no space for [mem size 0x01800000]
> > >     pci 0000:01:00.0: BAR 8: failed to assign [mem size 0x01800000]
> > >     pci 0000:02:03.0: BAR 8: no space for [mem size 0x01000000]
> > >     pci 0000:02:03.0: BAR 8: failed to assign [mem size 0x01000000]
> > >     pci 0000:02:07.0: BAR 8: no space for [mem size 0x00100000]
> > >     pci 0000:02:07.0: BAR 8: failed to assign [mem size 0x00100000]
> > >     pci 0000:03:00.0: BAR 0: no space for [mem size 0x01000000 64bit]
> > >     pci 0000:03:00.0: BAR 0: failed to assign [mem size 0x01000000 64bit]
> > >
> > > Due to bugs in U-Boot port for Turris Mox, the second range in Turris Mox
> > > kernel DTS file for PCIe must start at 16 MB offset. Otherwise U-Boot
> > > crashes during loading of kernel DTB file. This bug is present only in
> > > U-Boot code for Turris Mox and therefore other Armada 3700 devices are not
> > > affected by this bug. Bug is fixed in U-Boot version 2021.07.
> > >
> > > To not break booting new kernels on existing versions of U-Boot on Turris
> > > Mox, use first 16 MB range for IO and second range with rest of PCIe window
> > > for MEM.
> > 
> > Is there any depencey with the firs patch of this series ?
> > 
> > What happend if this patch is applied without the other ?
> 
> First patch is fixing reading and setting ranges configuration from DTS.
> Without first patch memory windows stays as they were in bootloader or
> in its default configuration. Which is that all 128 MB are transparently
> mapped to PCIe MEM space.
> 
> Therefore this second DTS patch does not fixes issue with IO space
> (kernel still crashes when accessing it). But allows to use all PCIe MEM
> space (due to bootloader / default configuration) and therefore allows
> to use more PCIe cards (which needs more PCIe MEM space).

So, the two patches are decoupled then ? We are not taking dts changes
through the PCI tree.

Besides: these dts patches are a nightmare for backward compatibility,
hopefully Rob can shed some light on whether what you are doing here
is advisable and how to sync the changes with kernel changes.

Lorenzo

> > Could you test it to see if any regression occure ?
> > 
> > Thanks,
> > 
> > Grégory
> > 
> > >
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > Fixes: 76f6386b25cc ("arm64: dts: marvell: Add Aardvark PCIe support for Armada 3700")
> > > ---
> > >  .../boot/dts/marvell/armada-3720-turris-mox.dts | 17 +++++++++++++++++
> > >  arch/arm64/boot/dts/marvell/armada-37xx.dtsi    | 11 +++++++++--
> > >  2 files changed, 26 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
> > > index 53e817c5f6f3..86b3025f174b 100644
> > > --- a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
> > > +++ b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts
> > > @@ -134,6 +134,23 @@
> > >  	pinctrl-0 = <&pcie_reset_pins &pcie_clkreq_pins>;
> > >  	status = "okay";
> > >  	reset-gpios = <&gpiosb 3 GPIO_ACTIVE_LOW>;
> > > +	/*
> > > +	 * U-Boot port for Turris Mox has a bug which always expects that "ranges" DT property
> > > +	 * contains exactly 2 ranges with 3 (child) address cells, 2 (parent) address cells and
> > > +	 * 2 size cells and also expects that the second range starts at 16 MB offset. If these
> > > +	 * conditions are not met then U-Boot crashes during loading kernel DTB file. PCIe address
> > > +	 * space is 128 MB long, so the best split between MEM and IO is to use fixed 16 MB window
> > > +	 * for IO and the rest 112 MB (64+32+16) for MEM, despite that maximal IO size is just 64 kB.
> > > +	 * This bug is not present in U-Boot ports for other Armada 3700 devices and is fixed in
> > > +	 * U-Boot version 2021.07. See relevant U-Boot commits (the last one contains fix):
> > > +	 * https://source.denx.de/u-boot/u-boot/-/commit/cb2ddb291ee6fcbddd6d8f4ff49089dfe580f5d7
> > > +	 * https://source.denx.de/u-boot/u-boot/-/commit/c64ac3b3185aeb3846297ad7391fc6df8ecd73bf
> > > +	 * https://source.denx.de/u-boot/u-boot/-/commit/4a82fca8e330157081fc132a591ebd99ba02ee33
> > > +	 */
> > > +	#address-cells = <3>;
> > > +	#size-cells = <2>;
> > > +	ranges = <0x81000000 0 0xe8000000   0 0xe8000000   0 0x01000000   /* Port 0 IO */
> > > +		  0x82000000 0 0xe9000000   0 0xe9000000   0 0x07000000>; /* Port 0 MEM */
> > >  
> > >  	/* enabled by U-Boot if PCIe module is present */
> > >  	status = "disabled";
> > > diff --git a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> > > index 7a2df148c6a3..dac3007f2ac1 100644
> > > --- a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> > > +++ b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
> > > @@ -488,8 +488,15 @@
> > >  			#interrupt-cells = <1>;
> > >  			msi-parent = <&pcie0>;
> > >  			msi-controller;
> > > -			ranges = <0x82000000 0 0xe8000000   0 0xe8000000 0 0x1000000 /* Port 0 MEM */
> > > -				  0x81000000 0 0xe9000000   0 0xe9000000 0 0x10000>; /* Port 0 IO*/
> > > +			/*
> > > +			 * The 128 MiB address range [0xe8000000-0xf0000000] is
> > > +			 * dedicated for PCIe and can be assigned to 8 windows
> > > +			 * with size a power of two. Use one 64 KiB window for
> > > +			 * IO at the end and the remaining seven windows
> > > +			 * (totaling 127 MiB) for MEM.
> > > +			 */
> > > +			ranges = <0x82000000 0 0xe8000000   0 0xe8000000   0 0x07f00000   /* Port 0 MEM */
> > > +				  0x81000000 0 0xefff0000   0 0xefff0000   0 0x00010000>; /* Port 0 IO */
> > >  			interrupt-map-mask = <0 0 0 7>;
> > >  			interrupt-map = <0 0 0 1 &pcie_intc 0>,
> > >  					<0 0 0 2 &pcie_intc 1>,
> > > -- 
> > > 2.20.1
> > >
> > 
> > -- 
> > Gregory Clement, Bootlin
> > Embedded Linux and Kernel engineering
> > http://bootlin.com