2020-04-29 20:21:13

by Martin Blumenstingl

Subject: [PATCH RFC v2 05/11] net: stmmac: dwmac-meson8b: Add the PRG_ETH0_ADJ_* bits

The PRG_ETH0_ADJ_* are used for applying the RGMII RX delay. The public
datasheets only have very limited description for these registers, but
Jianxin Pan provided more detailed documentation from an (unnamed)
Amlogic engineer. Add the PRG_ETH0_ADJ_* bits along with the improved
description.

Suggested-by: Jianxin Pan <[email protected]>
Signed-off-by: Martin Blumenstingl <[email protected]>
---
.../ethernet/stmicro/stmmac/dwmac-meson8b.c | 21 +++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
index 1d7526ee09dd..70075628c58e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-meson8b.c
@@ -48,6 +48,27 @@
#define PRG_ETH0_INVERTED_RMII_CLK BIT(11)
#define PRG_ETH0_TX_AND_PHY_REF_CLK BIT(12)

+/* Bypass (= 0, the signal from the GPIO input directly connects to the
+ * internal sampling) or enable (= 1) the internal logic for RXEN and RXD[3:0]
+ * timing tuning.
+ */
+#define PRG_ETH0_ADJ_ENABLE BIT(13)
+/* Controls whether the RXEN and RXD[3:0] signals should be aligned with the
+ * input RX rising/falling edge and sent to the Ethernet internals. This sets
+ * the automatically delay and skew automatically (internally).
+ */
+#define PRG_ETH0_ADJ_SETUP BIT(14)
+/* An internal counter based on the "timing-adjustment" clock. The counter is
+ * cleared on both, the falling and rising edge of the RX_CLK. This selects the
+ * delay (= the counter value) when to start sampling RXEN and RXD[3:0].
+ */
+#define PRG_ETH0_ADJ_DELAY GENMASK(19, 15)
+/* Adjusts the skew between each bit of RXEN and RXD[3:0]. If a signal has a
+ * large input delay, the bit for that signal (RXEN = bit 0, RXD[3] = bit 1,
+ * ...) can be configured to be 1 to compensate for a delay of about 1ns.
+ */
+#define PRG_ETH0_ADJ_SKEW GENMASK(24, 20)
+
#define MUX_CLK_NUM_PARENTS 2

struct meson8b_dwmac;
--
2.26.2

2020-05-01 15:37:31

by Andrew Lunn

Subject: Re: [PATCH RFC v2 05/11] net: stmmac: dwmac-meson8b: Add the PRG_ETH0_ADJ_* bits

On Wed, Apr 29, 2020 at 10:16:38PM +0200, Martin Blumenstingl wrote:
> The PRG_ETH0_ADJ_* are used for applying the RGMII RX delay. The public
> datasheets only have very limited description for these registers, but
> Jianxin Pan provided more detailed documentation from an (unnamed)
> Amlogic engineer. Add the PRG_ETH0_ADJ_* bits along with the improved
> description.
>
> Suggested-by: Jianxin Pan <[email protected]>
> Signed-off-by: Martin Blumenstingl <[email protected]>

Reviewed-by: Andrew Lunn <[email protected]>

Andrew