Hello!
On 07/30/2017 05:06 PM, Niklas Söderlund wrote:
WoL is enabled in the suspend callback by setting MagicPacket detection
and disabling all interrupts expect MagicPacket. In the resume path the
driver needs to reset the hardware to rearm the WoL logic, this prevents
the driver from simply restoring the registers and to take advantage of
that ravb was not suspended to reduce resume time. To reset the
hardware the driver closes the device, sets it in reset mode and reopens
the device just like it would do in a normal suspend/resume scenario
without WoL enabled, but it both closes and opens the device in the
resume callback since the device needs to be reset for WoL to work.
One quirk needed for WoL is that the module clock needs to be prevented
from being switched off by Runtime PM. To keep the clock alive the
suspend callback need to call clk_enable() directly to increase the
usage count of the clock. Then when Runtime PM decreases the clock usage
count it won't reach 0 and be switched off.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
[...]
diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 5931e859876c2aee..3d399f85417a83cf 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
[...]
@@ -2179,6 +2270,32 @@ static int __maybe_unused ravb_resume(struct device *dev)
struct ravb_private *priv = netdev_priv(ndev);
int ret = 0;
+ /* Reduce the usecount of the clock to zero and then
+ * restore it to its original value. This is done to force
+ * the clock to be re-enabled which is a workaround
+ * for renesas-cpg-mssr driver which do not enable clocks
+ * when resuming from PSCI suspend/resume.
+ *
+ * Without this workaround the driver fails to communicate
+ * with the hardware if WoL was enabled when the system
+ * entered PSCI suspend. This is due to that if WoL is enabled
+ * we explicitly keep the clock from being turned off when
+ * suspending, but in PSCI sleep power is cut so the clock
+ * is disabled anyhow, the clock driver is not aware of this
+ * so the clock is not turned back on when resuming.
+ *
+ * TODO: once the renesas-cpg-mssr suspend/resume is working
+ * this clock dance should be removed.
+ */
+ clk_disable(priv->clk);
+ clk_disable(priv->clk);
+ clk_enable(priv->clk);
+ clk_enable(priv->clk);
After a small chat with Niklas, it became clear that this dance should be
behind the *if* that follows. I'd also like to see this workaround as a
separate patch since the isse it addresses is R-Car gen3 specific (and thus
can be reverted once the CPG/MMSR driver is fixed)...
+
+ /* If WoL is enabled set reset mode to rearm the WoL logic */
+ if (priv->wol_enabled)
+ ravb_write(ndev, CCC_OPC_RESET, CCC);
+
/* All register have been reset to default values.
* Restore all registers which where setup at probe time and
* reopen device if it was running before system suspended.
@@ -2202,6 +2319,11 @@ static int __maybe_unused ravb_resume(struct device *dev)
ravb_write(ndev, priv->desc_bat_dma, DBAT);
if (netif_running(ndev)) {
+ if (priv->wol_enabled) {
+ ret = ravb_wol_restore(ndev);
+ if (ret)
+ return ret;
+ }
ret = ravb_open(ndev);
Hm, perhaps worth calling sh_eth_open() outside sh_eth_wol_restore() as well?
MBR, Sergei
