Re: [PATCH 5.10 81/97] MIPS: Loongson64: Enable DMA noncoherent support

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sun, Dec 31, 2023 at 10:33:19AM +0100, Salvatore Bonaccorso wrote:
> Hi,
> 
> On Sat, Dec 30, 2023 at 11:16:41PM +0000, Jiaxun Yang wrote:
> > 
> > 
> > 在2023年12月30日十二月 下午7:38，Salvatore Bonaccorso写道：
> > > Hi,
> > >
> > > On Mon, Dec 11, 2023 at 07:22:24PM +0100, Greg Kroah-Hartman wrote:
> > >> 5.10-stable review patch.  If anyone has any objections, please let me know.
> > >> 
> > >> ------------------
> > >> 
> > >> From: Jiaxun Yang <jiaxun.yang@flygoat.com>
> > >> 
> > >> commit edc0378eee00200a5bedf1bb9f00ad390e0d1bd4 upstream.
> > >> 
> > >> There are some Loongson64 systems come with broken coherent DMA
> > >> support, firmware will set a bit in boot_param and pass nocoherentio
> > >> in cmdline.
> > >> 
> > >> However nonconherent support was missed out when spin off Loongson-2EF
> > >> form Loongson64, and that boot_param change never made itself into
> > >> upstream.
> > >> 
> > >> Support DMA noncoherent properly to get those systems working.
> > >> 
> > >> Cc: stable@vger.kernel.org
> > >> Fixes: 71e2f4dd5a65 ("MIPS: Fork loongson2ef from loongson64")
> > >> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> > >> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> > >> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > >> ---
> > >>  arch/mips/Kconfig                                  |    2 ++
> > >>  arch/mips/include/asm/mach-loongson64/boot_param.h |    3 ++-
> > >>  arch/mips/loongson64/env.c                         |   10 +++++++++-
> > >>  3 files changed, 13 insertions(+), 2 deletions(-)
> > >> 
> > >> --- a/arch/mips/Kconfig
> > >> +++ b/arch/mips/Kconfig
> > >> @@ -468,6 +468,7 @@ config MACH_LOONGSON2EF
> > >>  
> > >>  config MACH_LOONGSON64
> > >>  	bool "Loongson 64-bit family of machines"
> > >> +	select ARCH_DMA_DEFAULT_COHERENT
> > >>  	select ARCH_SPARSEMEM_ENABLE
> > >>  	select ARCH_MIGHT_HAVE_PC_PARPORT
> > >>  	select ARCH_MIGHT_HAVE_PC_SERIO
> > >> @@ -1379,6 +1380,7 @@ config CPU_LOONGSON64
> > >>  	select CPU_SUPPORTS_MSA
> > >>  	select CPU_DIEI_BROKEN if !LOONGSON3_ENHANCEMENT
> > >>  	select CPU_MIPSR2_IRQ_VI
> > >> +	select DMA_NONCOHERENT
> > >>  	select WEAK_ORDERING
> > >>  	select WEAK_REORDERING_BEYOND_LLSC
> > >>  	select MIPS_ASID_BITS_VARIABLE
> > >> --- a/arch/mips/include/asm/mach-loongson64/boot_param.h
> > >> +++ b/arch/mips/include/asm/mach-loongson64/boot_param.h
> > >> @@ -117,7 +117,8 @@ struct irq_source_routing_table {
> > >>  	u64 pci_io_start_addr;
> > >>  	u64 pci_io_end_addr;
> > >>  	u64 pci_config_addr;
> > >> -	u32 dma_mask_bits;
> > >> +	u16 dma_mask_bits;
> > >> +	u16 dma_noncoherent;
> > >>  } __packed;
> > >>  
> > >>  struct interface_info {
> > >> --- a/arch/mips/loongson64/env.c
> > >> +++ b/arch/mips/loongson64/env.c
> > >> @@ -13,6 +13,8 @@
> > >>   * Copyright (C) 2009 Lemote Inc.
> > >>   * Author: Wu Zhangjin, wuzhangjin@gmail.com
> > >>   */
> > >> +
> > >> +#include <linux/dma-map-ops.h>
> > >>  #include <linux/export.h>
> > >>  #include <linux/pci_ids.h>
> > >>  #include <asm/bootinfo.h>
> > >> @@ -131,8 +133,14 @@ void __init prom_init_env(void)
> > >>  	loongson_sysconf.pci_io_base = eirq_source->pci_io_start_addr;
> > >>  	loongson_sysconf.dma_mask_bits = eirq_source->dma_mask_bits;
> > >>  	if (loongson_sysconf.dma_mask_bits < 32 ||
> > >> -		loongson_sysconf.dma_mask_bits > 64)
> > >> +			loongson_sysconf.dma_mask_bits > 64) {
> > >>  		loongson_sysconf.dma_mask_bits = 32;
> > >> +		dma_default_coherent = true;
> > >> +	} else {
> > >> +		dma_default_coherent = !eirq_source->dma_noncoherent;
> > >> +	}
> > >> +
> > >> +	pr_info("Firmware: Coherent DMA: %s\n", dma_default_coherent ? "on" : "off");
> > >>  
> > >>  	loongson_sysconf.restart_addr = boot_p->reset_system.ResetWarm;
> > >>  	loongson_sysconf.poweroff_addr = boot_p->reset_system.Shutdown;
> > >
> > > While preparing an update for Debian and finally building for all
> > > supported architecture, the builds for mipsel and mips64el were
> > > failing with:
> > >
> > > /<<PKGBUILDDIR>>/arch/mips/loongson64/env.c: In function 
> > > 'prom_init_env':
> > > /<<PKGBUILDDIR>>/arch/mips/loongson64/env.c:138:3: error: 
> > > 'dma_default_coherent' undeclared (first use in this function); did you 
> > > mean 'dma_free_coherent'?
> > >   138 |   dma_default_coherent = true;
> > >       |   ^~~~~~~~~~~~~~~~~~~~
> > >       |   dma_free_coherent
> > > /<<PKGBUILDDIR>>/arch/mips/loongson64/env.c:138:3: note: each 
> > > undeclared identifier is reported only once for each function it 
> > > appears in
> > > make[6]: *** [/<<PKGBUILDDIR>>/scripts/Makefile.build:291: 
> > > arch/mips/loongson64/env.o] Error 1
> > > make[6]: *** Waiting for unfinished jobs....
> > >
> > > Is here a prerequisite missing for the commit?
> > >
> > > Backporting though 6d4e9a8efe3d ("driver core: lift dma_default_coherent into
> > > common code") which is from 5.12-rc1 though seems too intrusive, correct? Would
> > > the alternative be to just revert the 3ee7e2faef87 ("MIPS: Loongson64: Enable
> > > DMA noncoherent support") commit which landed in 5.10.204?
> > 
> > Hi,
> > 
> > Sorry for not spotting the issue in the first place.
> > 
> > It actually requires more dependencies such as c00a60d6f4a1 ("of: address: always
> > use dma_default_coherent for default coherency").
> > 
> > I'll try to produce a backport series but better to drop this patch from stable
> > for now.
> 
> Thanks a lot for your quick reply! 
> 
> So I guess it only needs a revert for now from 5.10.y correct?
> 
> Greg, possible to already queue up the revert for 5.10.y for the next
> upload?

Now reverted, thanks.

greg k-h