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List:       linux-stable-commits
Subject:    Patch "Revert "MIPS: Alchemy: fix dbdma2"" has been added to the 4.19-stable tree
From:       <gregkh () linuxfoundation ! org>
Date:       2023-08-31 10:39:28
Message-ID: 2023083128-compel-gruffly-e4b5 () gregkh
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This is a note to let you know that I've just added the patch titled

    Revert "MIPS: Alchemy: fix dbdma2"

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     revert-mips-alchemy-fix-dbdma2.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From 1a4039bdcf972a7d2e469bb1a5ea616c4c2216fb Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 31 Aug 2023 12:30:23 +0200
Subject: Revert "MIPS: Alchemy: fix dbdma2"

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit a16419bae292d768546bcd6e0bfbf8a722756fee which is
commit 2d645604f69f3a772d58ead702f9a8e84ab2b342 upstream.

It breaks the build, so should be dropped.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/5b30ff73-46cb-1d1e-3823-f175dbfbd91b@roeck-us.net
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/mips/alchemy/common/dbdma.c |   27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

--- a/arch/mips/alchemy/common/dbdma.c
+++ b/arch/mips/alchemy/common/dbdma.c
@@ -30,7 +30,6 @@
  *
  */
 
-#include <linux/dma-map-ops.h> /* for dma_default_coherent */
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
@@ -624,18 +623,17 @@ u32 au1xxx_dbdma_put_source(u32 chanid,
 		dp->dscr_cmd0 &= ~DSCR_CMD0_IE;
 
 	/*
-	 * There is an erratum on certain Au1200/Au1550 revisions that could
-	 * result in "stale" data being DMA'ed. It has to do with the snoop
-	 * logic on the cache eviction buffer.  dma_default_coherent is set
-	 * to false on these parts.
+	 * There is an errata on the Au1200/Au1550 parts that could result
+	 * in "stale" data being DMA'ed. It has to do with the snoop logic on
+	 * the cache eviction buffer.  DMA_NONCOHERENT is on by default for
+	 * these parts. If it is fixed in the future, these dma_cache_inv will
+	 * just be nothing more than empty macros. See io.h.
 	 */
-	if (!dma_default_coherent)
-		dma_cache_wback_inv(KSEG0ADDR(buf), nbytes);
+	dma_cache_wback_inv((unsigned long)buf, nbytes);
 	dp->dscr_cmd0 |= DSCR_CMD0_V;	/* Let it rip */
 	wmb(); /* drain writebuffer */
 	dma_cache_wback_inv((unsigned long)dp, sizeof(*dp));
 	ctp->chan_ptr->ddma_dbell = 0;
-	wmb(); /* force doorbell write out to dma engine */
 
 	/* Get next descriptor pointer. */
 	ctp->put_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));
@@ -687,18 +685,17 @@ u32 au1xxx_dbdma_put_dest(u32 chanid, dm
 			  dp->dscr_source1, dp->dscr_dest0, dp->dscr_dest1);
 #endif
 	/*
-	 * There is an erratum on certain Au1200/Au1550 revisions that could
-	 * result in "stale" data being DMA'ed. It has to do with the snoop
-	 * logic on the cache eviction buffer.  dma_default_coherent is set
-	 * to false on these parts.
+	 * There is an errata on the Au1200/Au1550 parts that could result in
+	 * "stale" data being DMA'ed. It has to do with the snoop logic on the
+	 * cache eviction buffer.  DMA_NONCOHERENT is on by default for these
+	 * parts. If it is fixed in the future, these dma_cache_inv will just
+	 * be nothing more than empty macros. See io.h.
 	 */
-	if (!dma_default_coherent)
-		dma_cache_inv(KSEG0ADDR(buf), nbytes);
+	dma_cache_inv((unsigned long)buf, nbytes);
 	dp->dscr_cmd0 |= DSCR_CMD0_V;	/* Let it rip */
 	wmb(); /* drain writebuffer */
 	dma_cache_wback_inv((unsigned long)dp, sizeof(*dp));
 	ctp->chan_ptr->ddma_dbell = 0;
-	wmb(); /* force doorbell write out to dma engine */
 
 	/* Get next descriptor pointer. */
 	ctp->put_ptr = phys_to_virt(DSCR_GET_NXTPTR(dp->dscr_nxtptr));


Patches currently in stable-queue which might be from gregkh@linuxfoundation.org are

queue-4.19/revert-mips-alchemy-fix-dbdma2.patch
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