From ffaf5b92491d47bcecc22df9ba37d31dd2b357bc Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Fri, 27 Jan 2023 10:40:07 +0000 Subject: [PATCH] nvmem: sunxi_sid: Always use 32-bit MMIO reads commit c151d5ed8e8fe0474bd61dce7f2076ca5916c683 upstream. The SID SRAM on at least some SoCs (A64 and D1) returns different values when read with bus cycles narrower than 32 bits. This is not immediately obvious, because memcpy_fromio() uses word-size accesses as long as enough data is being copied. The vendor driver always uses 32-bit MMIO reads, so do the same here. This is faster than the register-based method, which is currently used as a workaround on A64. And it fixes the values returned on D1, where the SRAM method was being used. The special case for the last word is needed to maintain .word_size == 1 for sysfs ABI compatibility, as noted previously in commit 550c2103a74b ("nvmem: sunxi_sid: Optimize register read-out method"). Fixes: 9a1de683c1ff ("nvmem: sunxi_sid: Add support for D1 variant") Cc: stable@vger.kernel.org Tested-by: Heiko Stuebner Signed-off-by: Samuel Holland Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20230127104015.23839-3-srinivas.kandagatla@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/nvmem/sunxi_sid.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/nvmem/sunxi_sid.c b/drivers/nvmem/sunxi_sid.c index 5750e1f4bcdbb..92dfe4cb10e38 100644 --- a/drivers/nvmem/sunxi_sid.c +++ b/drivers/nvmem/sunxi_sid.c @@ -41,8 +41,21 @@ static int sunxi_sid_read(void *context, unsigned int offset, void *val, size_t bytes) { struct sunxi_sid *sid = context; + u32 word; + + /* .stride = 4 so offset is guaranteed to be aligned */ + __ioread32_copy(val, sid->base + sid->value_offset + offset, bytes / 4); - memcpy_fromio(val, sid->base + sid->value_offset + offset, bytes); + val += round_down(bytes, 4); + offset += round_down(bytes, 4); + bytes = bytes % 4; + + if (!bytes) + return 0; + + /* Handle any trailing bytes */ + word = readl_relaxed(sid->base + sid->value_offset + offset); + memcpy(val, &word, bytes); return 0; } -- 2.39.5