Re: [PATCH v2] net: stmmac: explicitly deassert GMAC_AHB_RESET

On 07/06/2021 10:45, Philipp Zabel wrote:

On Sun, 2021-06-06 at 11:30 +0100, Matthew Hagan wrote:

quoted

We are currently assuming that GMAC_AHB_RESET will already be deasserted
by the bootloader. However if this has not been done, probing of the GMAC
will fail. To remedy this we must ensure GMAC_AHB_RESET has been deasserted
prior to probing.

v2 changes:
 - remove NULL condition check for stmmac_ahb_rst in stmmac_main.c
 - unwrap dev_err() message in stmmac_main.c
 - add PTR_ERR() around plat->stmmac_ahb_rst in stmmac_platform.c

Signed-off-by: Matthew Hagan <redacted>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 4 ++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 7 +++++++
 include/linux/stmmac.h                                | 1 +
 3 files changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 6d41dd6f9f7a..0d4cb423cbbd 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -6840,6 +6840,10 @@ int stmmac_dvr_probe(struct device *device,
 			reset_control_reset(priv->plat->stmmac_rst);
 	}
 
+	ret = reset_control_deassert(priv->plat->stmmac_ahb_rst);
+	if (ret == -ENOTSUPP)
+		dev_err(priv->device, "unable to bring out of ahb reset\n");
+

I would make this

	if (ret)
		dev_err(priv->device, "unable to bring out of ahb reset: %pe\n", ERR_PTR(ret));

Done.

Also consider asserting the reset again in the remove path. Or is there
a reason not to?

Don't see any issue doing this. As this is a shared reset, the assert will only occur
when the final GMAC is removed, due to the tracking of deassert_count.

With that addressed,

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp

Thanks,

Matthew


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