Hi Christoph,
On Mon, Nov 21, 2022 at 10:56 AM Christoph Hellwig <hch@xxxxxx> wrote:
The m532x coldfire platforms can't properly implement dma_alloc_coherent
and currently just return noncoherent memory from it. The fec driver
than works around this with a flush of all caches in the receive path.
Make this hack a little less bad by using the explicit
dma_alloc_noncoherent API and documenting the hacky cache flushes.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Thanks for your patch!
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1580,6 +1580,10 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
struct page *page;
#ifdef CONFIG_M532x
+ /*
+ * Hacky flush of all caches instead of using the DMA API for the TSO
+ * headers.
+ */
flush_cache_all();
#endif
rxq = fep->rx_queue[queue_id];
@@ -3123,10 +3127,17 @@ static void fec_enet_free_queue(struct net_device *ndev)
for (i = 0; i < fep->num_tx_queues; i++)
if (fep->tx_queue[i] && fep->tx_queue[i]->tso_hdrs) {
txq = fep->tx_queue[i];
+#ifdef CONFIG_M532x
Shouldn't this be the !CONFIG_M532x path?
dma_free_coherent(&fep->pdev->dev,
txq->bd.ring_size * TSO_HEADER_SIZE,
txq->tso_hdrs,
txq->tso_hdrs_dma);
+#else
+ dma_free_noncoherent(&fep->pdev->dev,
+ txq->bd.ring_size * TSO_HEADER_SIZE,
+ txq->tso_hdrs, txq->tso_hdrs_dma,
+ DMA_BIDIRECTIONAL);
+#endif
}
for (i = 0; i < fep->num_rx_queues; i++)
@@ -3157,10 +3168,18 @@ static int fec_enet_alloc_queue(struct net_device *ndev)
txq->tx_wake_threshold =
(txq->bd.ring_size - txq->tx_stop_threshold) / 2;
+#ifdef CONFIG_M532x
Likewise
txq->tso_hdrs = dma_alloc_coherent(&fep->pdev->dev,
txq->bd.ring_size * TSO_HEADER_SIZE,
&txq->tso_hdrs_dma,
GFP_KERNEL);
+#else
+ /* m68knommu manually flushes all caches in fec_enet_rx_queue */
+ txq->tso_hdrs = dma_alloc_noncoherent(&fep->pdev->dev,
+ txq->bd.ring_size * TSO_HEADER_SIZE,
+ &txq->tso_hdrs_dma, DMA_BIDIRECTIONAL,
+ GFP_KERNEL);
+#endif
if (!txq->tso_hdrs) {
ret = -ENOMEM;
goto alloc_failed;
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
