linux-kernel - [PATCH net-next] bindings: net: stmmac: correctify note about LPI interrupt

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Date:   Thu,  9 Nov 2017 18:09:26 +0100
From:   Niklas Cassel <niklas.cassel@...s.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Niklas Cassel <niklass@...s.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Thierry Reding <treding@...dia.com>
Cc:     Niklas Cassel <niklass@...s.com>, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next] bindings: net: stmmac: correctify note about LPI interrupt

There are two different combined signal for various interrupt events:
In EQOS-CORE and EQOS-MTL configurations, mci_intr_o is the interrupt
signal.
In EQOS-DMA, EQOS-AHB and EQOS-AXI configurations, these interrupt events
are combined with the events in the DMA on the sbd_intr_o signal.

Depending on configuration, the device tree irq "macirq" will refer to
either mci_intr_o or sbd_intr_o.

The databook states:
"The MAC generates the LPI interrupt when the Tx or Rx side enters or exits
the LPI state. The interrupt mci_intr_o (sbd_intr_o in certain
configurations) is asserted when the LPI interrupt status is set.

When the MAC exits the Rx LPI state, then in addition to the mci_intr_o
(sbd_intr_o in certain configurations), the sideband signal lpi_intr_o is
asserted.

If you do not want to gate-off the application clock during the Rx LPI
state, you can leave the lpi_intr_o signal unconnected and use the
mci_intr_o (sbd_intr_o in certain configurations) signal to detect Rx LPI
exit."

Since the "macirq" is always raised when Tx or Rx enters/exits the LPI
state, "eth_lpi" must therefore refer to lpi_intr_o, which is only raised
when Rx exits the LPI state. Update the DT binding description to reflect
reality.

Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
---
 Documentation/devicetree/bindings/net/stmmac.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
index c3a7be6615c5..3a28a5d8857d 100644
--- a/Documentation/devicetree/bindings/net/stmmac.txt
+++ b/Documentation/devicetree/bindings/net/stmmac.txt
@@ -12,7 +12,7 @@ Required properties:
 	Valid interrupt names are:
   - "macirq" (combined signal for various interrupt events)
   - "eth_wake_irq" (the interrupt to manage the remote wake-up packet detection)
-  - "eth_lpi" (the interrupt that occurs when Tx or Rx enters/exits LPI state)
+  - "eth_lpi" (the interrupt that occurs when Rx exits the LPI state)
 - phy-mode: See ethernet.txt file in the same directory.
 - snps,reset-gpio 	gpio number for phy reset.
 - snps,reset-active-low boolean flag to indicate if phy reset is active low.
-- 
2.14.2