* Re: [PATCH] RISC-V: Define pgprot_dmacoherent() for non-coherent devices
[not found] <20250820152316.1012757-1-apatel@ventanamicro.com>
@ 2026-05-09 11:56 ` Vadim Akimov
0 siblings, 0 replies; only message in thread
From: Vadim Akimov @ 2026-05-09 11:56 UTC (permalink / raw)
To: Anup Patel
Cc: Rafael J . Wysocki, Sunil V L, Palmer Dabbelt, Paul Walmsley,
Alexandre Ghiti, Atish Patra, Andrew Jones, Anup Patel,
linux-riscv, linux-kernel, linux-sunxi
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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