On 11/1/23 2:39 PM, Jiaxun Yang wrote:
> 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 work.
Working.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 71e2f4dd5a65 ("MIPS: Fork loongson2ef from loongson64")
> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
[...]
> diff --git a/arch/mips/include/asm/mach-loongson64/boot_param.h b/arch/mips/include/asm/mach-loongson64/boot_param.h
> index 035b1a69e2d0..c454ef734c45 100644
> --- 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 {
> diff --git a/arch/mips/loongson64/env.c b/arch/mips/loongson64/env.c
> index c961e2999f15..df0e92cd3920 100644
> --- 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@xxxxxxxxx
> */
> +
> +#include <linux/dma-map-ops.h>
> #include <linux/export.h>
> #include <linux/pci_ids.h>
> #include <asm/bootinfo.h>
> @@ -147,8 +149,13 @@ void __init prom_lefi_init_env(void)
>
> 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) {
Please indent this line differently, so it doesn't blend
with the following line (either start it in the same column
as the *if* expression above, or add 1 more tab).
> loongson_sysconf.dma_mask_bits = 32;
> + dma_default_coherent = true;
> + } else
The kernel style dictates that you need to add {} on the *else*
branchh too.
> + dma_default_coherent = !eirq_source->dma_noncoherent;
> +
> + pr_info("DMA coherent: %s\n", dma_default_coherent ? "on" : "off");
Maybe "Coherent DMA: %s\n"?
[...]
MBR, Sergey
