Re: [PATCH 07/28] 53c700: improve non-coherent DMA handling

all subsystems

On Wed, 2020-08-19 at 08:55 +0200, Christoph Hellwig wrote:
Switch the 53c700 driver to only use non-coherent descriptor memory
if it really has to because dma_alloc_coherent fails.  This doesn't
matter for any of the platforms it runs on currently, but that will
change soon.

To help with this two new helpers to transfer ownership to and from
the device are added that abstract the syncing of the non-coherent
memory. The two current bidirectional cases are mapped to transfers
to the device, as that appears to what they are used for.  Note that
for parisc, which is the only architecture this driver needs to use
non-coherent memory on, the direction argument of dma_cache_sync is
ignored, so this will not change behavior in any way.
I think this looks mostly OK, except for one misnamed parameter below. 
Unfortunately, the last non-coherent parisc was the 700 series and I no
longer own a box, so I can't test that part of it (I can fire up the
C360 to test it on a coherent arch).

[...]

diff --git a/drivers/scsi/53c700.h b/drivers/scsi/53c700.h
index 05fe439b66afe5..0f545b05fe611d 100644
--- a/drivers/scsi/53c700.h
+++ b/drivers/scsi/53c700.h
@@ -209,6 +209,7 @@ struct NCR_700_Host_Parameters {
 #endif
 	__u32	chip710:1;	/* set if really a 710 not
700 */
 	__u32	burst_length:4;	/* set to 0 to disable
710 bursting */
+	__u32	noncoherent:1;	/* needs to use non-
coherent DMA */
 
 	/* NOTHING BELOW HERE NEEDS ALTERING */
 	__u32	fast:1;		/* if we can alter the
SCSI bus clock
@@ -429,7 +430,7 @@ struct NCR_700_Host_Parameters {
 	for(i=0; i< (sizeof(A_##symbol##_used) / sizeof(__u32));
i++) { \
 		__u32 val =
bS_to_cpu((script)[A_##symbol##_used[i]]) + da; \
 		(script)[A_##symbol##_used[i]] = bS_to_host(val); \
-		dma_cache_sync((dev),
&(script)[A_##symbol##_used[i]], 4, DMA_TO_DEVICE); \
+		dma_sync_to_dev((dev),
&(script)[A_##symbol##_used[i]], 4); \
 		DEBUG((" script, patching %s at %d to %pad\n", \
 		       #symbol, A_##symbol##_used[i], &da)); \
 	} \
@@ -441,7 +442,7 @@ struct NCR_700_Host_Parameters {
 	dma_addr_t da = value; \
 	for(i=0; i< (sizeof(A_##symbol##_used) / sizeof(__u32));
i++) { \
 		(script)[A_##symbol##_used[i]] = bS_to_host(da); \
-		dma_cache_sync((dev),
&(script)[A_##symbol##_used[i]], 4, DMA_TO_DEVICE); \
+		dma_sync_to_dev((dev),
&(script)[A_##symbol##_used[i]], 4); \
 		DEBUG((" script, patching %s at %d to %pad\n", \
 		       #symbol, A_##symbol##_used[i], &da)); \
 	} \
@@ -456,7 +457,7 @@ struct NCR_700_Host_Parameters {
 		val &= 0xff00ffff; \
 		val |= ((value) & 0xff) << 16; \
 		(script)[A_##symbol##_used[i]] = bS_to_host(val); \
-		dma_cache_sync((dev),
&(script)[A_##symbol##_used[i]], 4, DMA_TO_DEVICE); \
+		dma_sync_to_dev((dev),
&(script)[A_##symbol##_used[i]], 4); \
 		DEBUG((" script, patching ID field %s at %d to
0x%x\n", \
 		       #symbol, A_##symbol##_used[i], val)); \
 	} \
@@ -470,7 +471,7 @@ struct NCR_700_Host_Parameters {
 		val &= 0xffff0000; \
 		val |= ((value) & 0xffff); \
 		(script)[A_##symbol##_used[i]] = bS_to_host(val); \
-		dma_cache_sync((dev),
&(script)[A_##symbol##_used[i]], 4, DMA_TO_DEVICE); \
+		dma_sync_to_dev((dev),
&(script)[A_##symbol##_used[i]], 4); \
 		DEBUG((" script, patching short field %s at %d to
0x%x\n", \
 		       #symbol, A_##symbol##_used[i], val)); \
 	} \
These macro arguments need updating.  Since you changed the input from
hostdata->dev to hostdata, leaving the macro argument as dev is simply
misleading.  It needs to become hostdata or h.

James


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