2023-03-26 10:19:21 +00:00
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From 416f25a948d11ef15733f2e31658d31b5cc7bef6 Mon Sep 17 00:00:00 2001
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From: Thomas Nixon <tom@tomn.co.uk>
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Date: Sun, 26 Mar 2023 11:08:49 +0100
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Subject: [PATCH] mtd: rawnand: xway: don't yield while holding spinlock
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The nand driver normally while waiting for the device to become ready;
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this is normally fine, but xway_nand holds the ebu_lock spinlock, and
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this can cause lockups if other threads which use ebu_lock are
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interleaved. Fix this by waiting instead of polling.
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This mainly showed up as crashes in ath9k_pci_owl_loader (see
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https://github.com/openwrt/openwrt/issues/9829 ), but turning on
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spinlock debugging shows this happening in other places too.
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This doesn't seem to measurably impact boot time.
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Signed-off-by: Thomas Nixon <tom@tomn.co.uk>
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---
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drivers/mtd/nand/raw/xway_nand.c | 8 +++++++-
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1 file changed, 7 insertions(+), 1 deletion(-)
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--- a/drivers/mtd/nand/raw/xway_nand.c
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+++ b/drivers/mtd/nand/raw/xway_nand.c
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2024-05-14 09:05:34 +00:00
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@@ -176,7 +176,13 @@ static void xway_cmd_ctrl(struct nand_ch
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2023-03-26 10:19:21 +00:00
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static int xway_dev_ready(struct nand_chip *chip)
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{
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- return ltq_ebu_r32(EBU_NAND_WAIT) & NAND_WAIT_RD;
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+ /*
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+ * wait until ready, as otherwise the driver will yield in nand_wait or
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+ * nand_wait_ready, which is a bad idea when we're holding ebu_lock
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+ */
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+ while ((ltq_ebu_r32(EBU_NAND_WAIT) & NAND_WAIT_RD) == 0)
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+ cpu_relax();
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+ return 1;
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}
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static unsigned char xway_read_byte(struct nand_chip *chip)
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