linux-kernel - Re: [PATCH] riscv: mm: update T-Head memory type definitions

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Message-ID: <ZPY8iB6BV9wXTqPV@x1>
Date:   Mon, 4 Sep 2023 13:22:32 -0700
From:   Drew Fustini <dfustini@...libre.com>
To:     Jisheng Zhang <jszhang@...nel.org>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>, Guo Ren <guoren@...nel.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] riscv: mm: update T-Head memory type definitions

On Sun, Aug 27, 2023 at 05:06:44PM +0800, Jisheng Zhang wrote:
> Update T-Head memory type definitions according to C910 doc [1]
> For NC and IO, SH property isn't configurable, hardcoded as SH,
> so set SH for NOCACHE and IO.
> 
> And also set bit[61](Bufferable) for NOCACHE according to the
> table 6.1 in the doc [1].
> 
> Link: https://github.com/T-head-Semi/openc910 [1]
> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
> ---
>  arch/riscv/include/asm/pgtable-64.h | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
> index 7a5097202e15..9a2c780a11e9 100644
> --- a/arch/riscv/include/asm/pgtable-64.h
> +++ b/arch/riscv/include/asm/pgtable-64.h
> @@ -126,14 +126,18 @@ enum napot_cont_order {
>  
>  /*
>   * [63:59] T-Head Memory Type definitions:
> - *
> - * 00000 - NC   Weakly-ordered, Non-cacheable, Non-bufferable, Non-shareable, Non-trustable
> + * bit[63] SO - Strong Order
> + * bit[62] C - Cacheable
> + * bit[61] B - Bufferable
> + * bit[60] SH - Shareable
> + * bit[59] Sec - Trustable
> + * 00110 - NC   Weakly-ordered, Non-cacheable, Bufferable, Shareable, Non-trustable
>   * 01110 - PMA  Weakly-ordered, Cacheable, Bufferable, Shareable, Non-trustable
> - * 10000 - IO   Strongly-ordered, Non-cacheable, Non-bufferable, Non-shareable, Non-trustable
> + * 10010 - IO   Strongly-ordered, Non-cacheable, Non-bufferable, Shareable, Non-trustable
>   */
>  #define _PAGE_PMA_THEAD		((1UL << 62) | (1UL << 61) | (1UL << 60))
> -#define _PAGE_NOCACHE_THEAD	0UL
> -#define _PAGE_IO_THEAD		(1UL << 63)
> +#define _PAGE_NOCACHE_THEAD	((1UL < 61) | (1UL << 60))
> +#define _PAGE_IO_THEAD		((1UL << 63) | (1UL << 60))
>  #define _PAGE_MTMASK_THEAD	(_PAGE_PMA_THEAD | _PAGE_IO_THEAD | (1UL << 59))
>  
>  static inline u64 riscv_page_mtmask(void)
> -- 
> 2.40.1
> 

Tested-by: Drew Fustini <dfustini@...libre.com>

I applied this on top of:

 [1] riscv: errata: improve T-Head CMO
 [2] riscv: dts: thead: set dma-noncoherent to soc bus
 [3] RISC-V: Add basic eMMC support for BeagleV Ahead 

The BeagleV Ahead eMMC continues to function okay in ADMA mode after
this patch was applied.

Thanks,
Drew

[1] https://lore.kernel.org/linux-riscv/20230827090813.1353-1-jszhang@kernel.org/
[2] https://lore.kernel.org/linux-riscv/ZOIBQI3L4kP7c%2FT1@xhacker/
[3] https://lore.kernel.org/linux-riscv/20230724-th1520-emmc-v2-0-132ed2e2171e@baylibre.com/