git: 04d2d2d7fd22 - main - cgem: improve usage of busdma(9) KPI
Mitchell Horne
mhorne at FreeBSD.org
Thu Feb 18 21:19:36 UTC 2021
The branch main has been updated by mhorne:
URL: https://cgit.FreeBSD.org/src/commit/?id=04d2d2d7fd22bba638ccb5a0b2e0805087a70cd3
commit 04d2d2d7fd22bba638ccb5a0b2e0805087a70cd3
Author: Mitchell Horne <mhorne at FreeBSD.org>
AuthorDate: 2021-01-20 15:07:53 +0000
Commit: Mitchell Horne <mhorne at FreeBSD.org>
CommitDate: 2021-02-18 21:17:41 +0000
cgem: improve usage of busdma(9) KPI
BUS_DMA_NOCACHE should only be used when one needs to guarantee the
created mapping has uncached memory attributes, usually as a result
of buggy hardware. Normal use cases should pass BUS_DMA_COHERENT, to
create an appropriate mapping based on the flags passed to
bus_dma_tag_create().
This should have no functional change, since the DMA tags in this driver
are created without the BUS_DMA_COHERENT flag.
Reported by: mmel
Reviewed by: mmel, Thomas Skibo <thomas-bsd at skibo.net>
MFC after: 3 days
---
sys/dev/cadence/if_cgem.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/sys/dev/cadence/if_cgem.c b/sys/dev/cadence/if_cgem.c
index 81fc39b831af..0583e846458a 100644
--- a/sys/dev/cadence/if_cgem.c
+++ b/sys/dev/cadence/if_cgem.c
@@ -443,17 +443,13 @@ cgem_setup_descs(struct cgem_softc *sc)
return (err);
/*
- * Allocate DMA memory in non-cacheable space. We allocate transmit,
- * receive and null descriptor queues all at once because the
- * hardware only provides one register for the upper 32 bits of
- * rx and tx descriptor queues hardware addresses.
+ * Allocate DMA memory. We allocate transmit, receive and null
+ * descriptor queues all at once because the hardware only provides
+ * one register for the upper 32 bits of rx and tx descriptor queues
+ * hardware addresses.
*/
err = bus_dmamem_alloc(sc->desc_dma_tag, (void **)&sc->rxring,
-#ifdef __arm__
BUS_DMA_NOWAIT | BUS_DMA_COHERENT | BUS_DMA_ZERO,
-#else
- BUS_DMA_NOWAIT | BUS_DMA_NOCACHE | BUS_DMA_ZERO,
-#endif
&sc->rxring_dma_map);
if (err)
return (err);
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