git: 04d2d2d7fd22 - main - cgem: improve usage of busdma(9) KPI

[Mitchell Horne]

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);