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56 lines
2.0 KiB
Diff
56 lines
2.0 KiB
Diff
From c151d5ed8e8fe0474bd61dce7f2076ca5916c683 Mon Sep 17 00:00:00 2001
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From: Samuel Holland <samuel@sholland.org>
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Date: Fri, 27 Jan 2023 10:40:07 +0000
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Subject: [PATCH] nvmem: sunxi_sid: Always use 32-bit MMIO reads
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The SID SRAM on at least some SoCs (A64 and D1) returns different values
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when read with bus cycles narrower than 32 bits. This is not immediately
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obvious, because memcpy_fromio() uses word-size accesses as long as
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enough data is being copied.
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The vendor driver always uses 32-bit MMIO reads, so do the same here.
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This is faster than the register-based method, which is currently used
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as a workaround on A64. And it fixes the values returned on D1, where
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the SRAM method was being used.
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The special case for the last word is needed to maintain .word_size == 1
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for sysfs ABI compatibility, as noted previously in commit de2a3eaea552
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("nvmem: sunxi_sid: Optimize register read-out method").
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Fixes: 07ae4fde9efa ("nvmem: sunxi_sid: Add support for D1 variant")
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Cc: stable@vger.kernel.org
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Tested-by: Heiko Stuebner <heiko@sntech.de>
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Signed-off-by: Samuel Holland <samuel@sholland.org>
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Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
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Link: https://lore.kernel.org/r/20230127104015.23839-3-srinivas.kandagatla@linaro.org
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/nvmem/sunxi_sid.c | 15 ++++++++++++++-
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1 file changed, 14 insertions(+), 1 deletion(-)
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--- a/drivers/nvmem/sunxi_sid.c
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+++ b/drivers/nvmem/sunxi_sid.c
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@@ -41,8 +41,21 @@ static int sunxi_sid_read(void *context,
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void *val, size_t bytes)
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{
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struct sunxi_sid *sid = context;
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+ u32 word;
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- memcpy_fromio(val, sid->base + sid->value_offset + offset, bytes);
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+ /* .stride = 4 so offset is guaranteed to be aligned */
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+ __ioread32_copy(val, sid->base + sid->value_offset + offset, bytes / 4);
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+
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+ val += round_down(bytes, 4);
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+ offset += round_down(bytes, 4);
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+ bytes = bytes % 4;
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+
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+ if (!bytes)
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+ return 0;
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+
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+ /* Handle any trailing bytes */
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+ word = readl_relaxed(sid->base + sid->value_offset + offset);
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+ memcpy(val, &word, bytes);
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return 0;
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}
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