sata_mv: workaround errata SATA#13 (12f3b6d7) · Commits · 戴 / test

Add remainder of workaround for errata SATA#13. This prevents writes of certain adjacent 32-bit registers from being combined into single 64-bit writes, which might fail for the affected registers. Most of sata_mv is already safe from this issue, but adding this code to mv_write_cached_reg() will catch the remaining cases and hopefully prevent future ones. Signed-off-by:

Mark Lord <mlord@pobox.com> Signed-off-by:

Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_mv.c

+19 −1

Original line number	Diff line number	Diff line
		@@ -919,8 +919,26 @@ static void mv_save_cached_regs(struct ata_port *ap)
		static inline void mv_write_cached_reg(void __iomem addr, u32 old, u32 new)
		{
		if (new != *old) {
		unsigned long laddr;
		*old = new;
		writel(new, addr);
		/*
		* Workaround for 88SX60x1-B2 FEr SATA#13:
		* Read-after-write is needed to prevent generating 64-bit
		* write cycles on the PCI bus for SATA interface registers
		* at offsets ending in 0x4 or 0xc.
		*
		* Looks like a lot of fuss, but it avoids an unnecessary
		* +1 usec read-after-write delay for unaffected registers.
		*/
		laddr = (long)addr & 0xffff;
		if (laddr >= 0x300 && laddr <= 0x33c) {
		laddr &= 0x000f;
		if (laddr == 0x4 \|\| laddr == 0xc) {
		writelfl(new, addr); /* read after write */
		return;
		}
		}
		writel(new, addr); /* unaffected by the errata */
		}
		}

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