This is a note to let you know that I've just added the patch titled
net: axienet: Autodetect 64-bit DMA capability
to the 5.4-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:
net-axienet-autodetect-64-bit-dma-capability.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d9a1d217fbdfba5ac225fa4bf7ef2a2c59597e9c
Author: Andre Przywara <andre.przywara@xxxxxxx>
Date: Tue Mar 24 13:23:46 2020 +0000
net: axienet: Autodetect 64-bit DMA capability
[ Upstream commit f735c40ed93ccaeb52d026def47ac1a423df7133 ]
When newer revisions of the Axienet IP are configured for a 64-bit bus,
we *need* to write to the MSB part of the an address registers,
otherwise the IP won't recognise this as a DMA start condition.
This is even true when the actual DMA address comes from the lower 4 GB.
To autodetect this configuration, at probe time we write all 1's to such
an MSB register, and see if any bits stick. If this is configured for a
32-bit bus, those MSB registers are RES0, so reading back 0 indicates
that no MSB writes are necessary.
On the other hands reading anything other than 0 indicated the need to
write the MSB registers, so we set the respective flag.
The actual DMA mask stays at 32-bit for now. To help bisecting, a
separate patch will enable allocations from higher addresses.
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Stable-dep-of: 9ff2f816e2aa ("net: axienet: Fix register defines comment description")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h b/drivers/net/ethernet/xilinx/xilinx_axienet.h
index 84c4c3655516a..fbaf3c987d9c1 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
@@ -161,6 +161,7 @@
#define XAE_FCC_OFFSET 0x0000040C /* Flow Control Configuration */
#define XAE_EMMC_OFFSET 0x00000410 /* EMAC mode configuration */
#define XAE_PHYC_OFFSET 0x00000414 /* RGMII/SGMII configuration */
+#define XAE_ID_OFFSET 0x000004F8 /* Identification register */
#define XAE_MDIO_MC_OFFSET 0x00000500 /* MII Management Config */
#define XAE_MDIO_MCR_OFFSET 0x00000504 /* MII Management Control */
#define XAE_MDIO_MWD_OFFSET 0x00000508 /* MII Management Write Data */
diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index 5440f39c5760d..1156719210cdb 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -152,6 +152,9 @@ static void axienet_dma_out_addr(struct axienet_local *lp, off_t reg,
dma_addr_t addr)
{
axienet_dma_out32(lp, reg, lower_32_bits(addr));
+
+ if (lp->features & XAE_FEATURE_DMA_64BIT)
+ axienet_dma_out32(lp, reg + 4, upper_32_bits(addr));
}
static void desc_set_phys_addr(struct axienet_local *lp, dma_addr_t addr,
@@ -1954,6 +1957,29 @@ static int axienet_probe(struct platform_device *pdev)
goto free_netdev;
}
+ /* Autodetect the need for 64-bit DMA pointers.
+ * When the IP is configured for a bus width bigger than 32 bits,
+ * writing the MSB registers is mandatory, even if they are all 0.
+ * We can detect this case by writing all 1's to one such register
+ * and see if that sticks: when the IP is configured for 32 bits
+ * only, those registers are RES0.
+ * Those MSB registers were introduced in IP v7.1, which we check first.
+ */
+ if ((axienet_ior(lp, XAE_ID_OFFSET) >> 24) >= 0x9) {
+ void __iomem *desc = lp->dma_regs + XAXIDMA_TX_CDESC_OFFSET + 4;
+
+ iowrite32(0x0, desc);
+ if (ioread32(desc) == 0) { /* sanity check */
+ iowrite32(0xffffffff, desc);
+ if (ioread32(desc) > 0) {
+ lp->features |= XAE_FEATURE_DMA_64BIT;
+ dev_info(&pdev->dev,
+ "autodetected 64-bit DMA range\n");
+ }
+ iowrite32(0x0, desc);
+ }
+ }
+
/* Check for Ethernet core IRQ (optional) */
if (lp->eth_irq <= 0)
dev_info(&pdev->dev, "Ethernet core IRQ not defined\n");
