When the Qualcomm ethqos driver is properly described in its associated
GDSC power-domain, the hardware will be powered down and loose its state
between qcom_ethqos_probe() and stmmac_init_dma_engine().
The result of this is that the functional clock from the RGMII IO macro
is no longer provides and the DMA software reset in dwmac4_dma_reset()
will time out, due to lacking clock signal.
Re-enable the functional clock, as part of the Qualcomm specific clock
enablement sequence to avoid this problem.
The final clock configuration will be adjusted by ethqos_fix_mac_speed()
once the link is being brought up.
Fixes: a7c30e62d4b8 ("net: stmmac: Add driver for Qualcomm ethqos")
Signed-off-by: Bjorn Andersson <[email protected]>
---
drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
index 0cc28c79cc61..835caa15d55f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -487,6 +487,13 @@ static int ethqos_clks_config(void *priv, bool enabled)
dev_err(ðqos->pdev->dev, "rgmii_clk enable failed\n");
return ret;
}
+
+ /* Enable functional clock to prevent DMA reset to timeout due
+ * to lacking PHY clock after the hardware block has been power
+ * cycled. The actual configuration will be adjusted once
+ * ethqos_fix_mac_speed() is invoked.
+ */
+ ethqos_set_func_clk_en(ethqos);
} else {
clk_disable_unprepare(ethqos->rgmii_clk);
}
--
2.33.1
+Cc: stable tree as I think this is an important fix for stmmac
dwmac-qcom-ethernet driver and affects ethernet functionality on QCOM
boards which use this driver.
More below..
On Wed, 23 Mar 2022 at 09:01, Bjorn Andersson
<[email protected]> wrote:
>
> When the Qualcomm ethqos driver is properly described in its associated
> GDSC power-domain, the hardware will be powered down and loose its state
> between qcom_ethqos_probe() and stmmac_init_dma_engine().
>
> The result of this is that the functional clock from the RGMII IO macro
> is no longer provides and the DMA software reset in dwmac4_dma_reset()
> will time out, due to lacking clock signal.
>
> Re-enable the functional clock, as part of the Qualcomm specific clock
> enablement sequence to avoid this problem.
>
> The final clock configuration will be adjusted by ethqos_fix_mac_speed()
> once the link is being brought up.
>
> Fixes: a7c30e62d4b8 ("net: stmmac: Add driver for Qualcomm ethqos")
> Signed-off-by: Bjorn Andersson <[email protected]>
> ---
> drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> index 0cc28c79cc61..835caa15d55f 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
> @@ -487,6 +487,13 @@ static int ethqos_clks_config(void *priv, bool enabled)
> dev_err(ðqos->pdev->dev, "rgmii_clk enable failed\n");
> return ret;
> }
> +
> + /* Enable functional clock to prevent DMA reset to timeout due
> + * to lacking PHY clock after the hardware block has been power
> + * cycled. The actual configuration will be adjusted once
> + * ethqos_fix_mac_speed() is invoked.
> + */
> + ethqos_set_func_clk_en(ethqos);
> } else {
> clk_disable_unprepare(ethqos->rgmii_clk);
> }
> --
> 2.33.1
Thanks for the catch, Bjorn. I tested this on the SA8155p-ADP board
and the eth interface can be moved from 'on' to 'off' state and
vice-versa properly after this change and we no longer need the EMAC
GDSC quirk, so:
Tested-and-Reviewed-by: Bhupesh Sharma <[email protected]>
Regards.
On Thu, Mar 24, 2022 at 03:08:08PM +0530, Bhupesh Sharma wrote:
> +Cc: stable tree as I think this is an important fix for stmmac
> dwmac-qcom-ethernet driver and affects ethernet functionality on QCOM
> boards which use this driver.
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
Hello:
This patch was applied to netdev/net.git (master)
by Jakub Kicinski <[email protected]>:
On Tue, 22 Mar 2022 20:32:55 -0700 you wrote:
> When the Qualcomm ethqos driver is properly described in its associated
> GDSC power-domain, the hardware will be powered down and loose its state
> between qcom_ethqos_probe() and stmmac_init_dma_engine().
>
> The result of this is that the functional clock from the RGMII IO macro
> is no longer provides and the DMA software reset in dwmac4_dma_reset()
> will time out, due to lacking clock signal.
>
> [...]
Here is the summary with links:
- net: stmmac: dwmac-qcom-ethqos: Enable RGMII functional clock on resume
https://git.kernel.org/netdev/net/c/ffba2123e171
You are awesome, thank you!
--
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