net: stmmac: add support for independent DMA pbl for tx/rx

GMAC and newer supports independent programmable burst lengths for
DMA tx/rx. Add new optional devicetree properties representing this.

To be backwards compatible, snps,pbl will still be valid, but
snps,txpbl/snps,rxpbl will override the value in snps,pbl if set.

If the IP is synthesized to use the AXI interface, there is a register
and a matching DT property inside the optional stmmac-axi-config DT node
for controlling burst lengths, named snps,blen.
However, using this register, it is not possible to control tx and rx
independently. Also, this register is not available if the IP was
synthesized with, e.g., the AHB interface.

Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Acked-by: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 6 deletions

diff --git a/Documentation/networking/stmmac.txt b/Documentation/networking/stmmac.txt
index 014f4f756cb7..6add57374f70 100644
--- a/Documentation/networking/stmmac.txt
+++ b/Documentation/networking/stmmac.txt
@@ -153,7 +153,8 @@ Where:
    o pbl: the Programmable Burst Length is maximum number of beats to
        be transferred in one DMA transaction.
        GMAC also enables the 4xPBL by default.
-   o fixed_burst/mixed_burst/burst_len
+   o txpbl/rxpbl: GMAC and newer supports independent DMA pbl for tx/rx.
+   o fixed_burst/mixed_burst/aal
  o clk_csr: fixed CSR Clock range selection.
  o has_gmac: uses the GMAC core.
  o enh_desc: if sets the MAC will use the enhanced descriptor structure.
@@ -205,16 +206,22 @@ tuned according to the HW capabilities.
 
 struct stmmac_dma_cfg {
 	int pbl;
+	int txpbl;
+	int rxpbl;
 	int fixed_burst;
-	int burst_len_supported;
+	int mixed_burst;
+	bool aal;
 };
 
 Where:
- o pbl: Programmable Burst Length
+ o pbl: Programmable Burst Length (tx and rx)
+ o txpbl: Transmit Programmable Burst Length. Only for GMAC and newer.
+	 If set, DMA tx will use this value rather than pbl.
+ o rxpbl: Receive Programmable Burst Length. Only for GMAC and newer.
+	 If set, DMA rx will use this value rather than pbl.
  o fixed_burst: program the DMA to use the fixed burst mode
- o burst_len: this is the value we put in the register
-	      supported values are provided as macros in
-	      linux/stmmac.h header file.
+ o mixed_burst: program the DMA to use the mixed burst mode
+ o aal: Address-Aligned Beats
 
 ---