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From: Vadim Akimov <lvd2@ziggo.nl>
To: Anup Patel <apatel@ventanamicro.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>,
	Atish Patra <atish.patra@linux.dev>,
	Anup Patel <anup@brainfault.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	linux-riscv@lists.infradead.org, linux-sunxi@lists.linux.dev,
	Andrew Jones <ajones@ventanamicro.com>
Subject: Re: [PATCH] RISC-V: Define pgprot_dmacoherent() for non-coherent devices
Date: Sat, 9 May 2026 13:56:12 +0200	[thread overview]
Message-ID: <af8g3DlQhHSME-0_@pivobook> (raw)
In-Reply-To: <20250820152316.1012757-1-apatel@ventanamicro.com>

Hi,

On Wed, Aug 20, 2025 at 08:53:16PM +0530, Anup Patel wrote:

> The pgprot_dmacoherent() is used when allocating memory for
> non-coherent devices and by default pgprot_dmacoherent() is
> same as pgprot_noncached() unless architecture overrides it.
 
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 91697fbf1f90..00d8bdaf1e8d 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h

> +#define pgprot_dmacoherent pgprot_writecombine

This single-line patch, as implemented in commit 00b58d2c25d10fecffbebaa0c369fc9d0a6de397 for 6.6.y,
breaks allwinner D1 SDcard handling:

[    0.000000] Linux version 6.6.115 (surfin@nedoserver) (riscv64-unknown-linux-gnu-gcc () 11.3.0, GNU ld (GNU Binutils) 2.38) #1 Tue May  5 10:25:47 MSK 2026

[    4.886823] sunxi-mmc 4020000.mmc: Got CD GPIO
[    4.893625] sunxi-mmc 4021000.mmc: allocated mmc-pwrseq
[    4.941711] sunxi-mmc 4021000.mmc: initialized, max. request size: 2048 KB, uses new timings mode
[    4.958033] sunxi-mmc 4020000.mmc: initialized, max. request size: 2048 KB, uses new timings mode
[    4.990692] sunxi-mmc 4021000.mmc: card claims to support voltages below defined range
[    5.009712] mmc1: new high speed SDIO card at address 0001

then following never happens with that patch, i.e. no SD card is found.

#[    5.109896] mmc0: new high speed SDHC card at address 0001
#[    5.116546] mmcblk0: mmc0:0001 EB1QT 29.8 GiB
#[    5.128887]  mmcblk0: p1 p2


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WARNING: multiple messages have this Message-ID (diff)
From: Vadim Akimov <lvd2@ziggo.nl>
To: Anup Patel <apatel@ventanamicro.com>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>,
	Sunil V L <sunilvl@ventanamicro.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Atish Patra <atish.patra@linux.dev>,
	Andrew Jones <ajones@ventanamicro.com>,
	Anup Patel <anup@brainfault.org>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-sunxi@lists.linux.dev
Subject: Re: [PATCH] RISC-V: Define pgprot_dmacoherent() for non-coherent devices
Date: Sat, 9 May 2026 13:56:12 +0200	[thread overview]
Message-ID: <af8g3DlQhHSME-0_@pivobook> (raw)
In-Reply-To: <20250820152316.1012757-1-apatel@ventanamicro.com>

Hi,

On Wed, Aug 20, 2025 at 08:53:16PM +0530, Anup Patel wrote:

> The pgprot_dmacoherent() is used when allocating memory for
> non-coherent devices and by default pgprot_dmacoherent() is
> same as pgprot_noncached() unless architecture overrides it.
 
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 91697fbf1f90..00d8bdaf1e8d 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h

> +#define pgprot_dmacoherent pgprot_writecombine

This single-line patch, as implemented in commit 00b58d2c25d10fecffbebaa0c369fc9d0a6de397 for 6.6.y,
breaks allwinner D1 SDcard handling:

[    0.000000] Linux version 6.6.115 (surfin@nedoserver) (riscv64-unknown-linux-gnu-gcc () 11.3.0, GNU ld (GNU Binutils) 2.38) #1 Tue May  5 10:25:47 MSK 2026

[    4.886823] sunxi-mmc 4020000.mmc: Got CD GPIO
[    4.893625] sunxi-mmc 4021000.mmc: allocated mmc-pwrseq
[    4.941711] sunxi-mmc 4021000.mmc: initialized, max. request size: 2048 KB, uses new timings mode
[    4.958033] sunxi-mmc 4020000.mmc: initialized, max. request size: 2048 KB, uses new timings mode
[    4.990692] sunxi-mmc 4021000.mmc: card claims to support voltages below defined range
[    5.009712] mmc1: new high speed SDIO card at address 0001

then following never happens with that patch, i.e. no SD card is found.

#[    5.109896] mmc0: new high speed SDHC card at address 0001
#[    5.116546] mmcblk0: mmc0:0001 EB1QT 29.8 GiB
#[    5.128887]  mmcblk0: p1 p2


  parent reply	other threads:[~2026-05-09 11:56 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-20 15:23 [PATCH] RISC-V: Define pgprot_dmacoherent() for non-coherent devices Anup Patel
2025-08-20 15:23 ` Anup Patel
2025-10-12  6:07 ` Guo Ren
2025-10-12  6:07   ` Guo Ren
2025-10-12  6:59   ` Guo Ren
2025-10-12  6:59     ` Guo Ren
2025-10-12 10:00 ` Han Gao (Revy)
2025-10-12 10:00   ` Han Gao (Revy)
2025-10-18 16:01 ` patchwork-bot+linux-riscv
2025-10-18 16:01   ` patchwork-bot+linux-riscv
2026-05-09 11:56 ` Vadim Akimov [this message]
2026-05-09 11:56   ` Vadim Akimov

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