Re: [RFC PATCH v5 3/4] phy: rockchip-pcie: Enable all four lanes

Robin Murphy
2025-06-20T12:47:40Z

On 2025-06-20 1:26 pm, Geraldo Nascimento wrote:
> On Fri, Jun 20, 2025 at 01:04:46PM +0100, Robin Murphy wrote:
>> On 2025-06-13 6:03 pm, Geraldo Nascimento wrote:
>>> Current code enables only Lane 0 because pwr_cnt will be incremented
>>> on first call to the function. Use for-loop to enable all 4 lanes
>>> through GRF.
>>
>> If this was really necessary, then surely it would also need the
>> equivalent changes in rockchip_pcie_phy_power_off() too?
>>
>> However, I'm not sure it *is* necessary - the NVMe on my RK3399 board
>> happily claims to be using an x4 link, so I stuck a print of inst->index
>> in this function, and sure enough I do see it being called for each
>> instance already:
>>
>> [ 1.737479] phy phy-ff770000.syscon:pcie-phy.1: power_on 0
>> [ 1.738810] phy phy-ff770000.syscon:pcie-phy.2: power_on 1
>> [ 1.745193] phy phy-ff770000.syscon:pcie-phy.3: power_on 2
>> [ 1.745196] phy phy-ff770000.syscon:pcie-phy.4: power_on 3
>>
>
> Hi Robin, and thanks for caring, it's excellent to rely on your
> extensive expertise on ARM in general and RK3399 specifically!
>
> However, on my board I'm positive it does not work without proposed
> patch and I get stuck with x1 link without it.
>
> There are currently very similar patches applied downstream to Armbian
> and OpenWRT so at least I'm confident that is not only my board which is
> quirky and other people experienced the same problem.

Ah, I put that print at the top of the function - on second look now I
see that there's an awkward mix of per-lane and global data, and pwr_cnt
is actually the latter. Sure enough, moving the print past that check I
only see it once.

However, I still don't think blindly enabling all the lanes is the right
thing to do either; I'd imagine something like the (untested) diff below
would be more appropriate. That would then seem to balance with what
power_off is doing.

Thanks,
Robin.

----->8-----
diff --git a/drivers/phy/rockchip/phy-rockchip-pcie.c b/drivers/phy/rockchip/phy-rockchip-pcie.c
index bd44af36c67a..a34a983db16c 100644
--- a/drivers/phy/rockchip/phy-rockchip-pcie.c
+++ b/drivers/phy/rockchip/phy-rockchip-pcie.c
@@ -160,11 +160,8 @@ static int rockchip_pcie_phy_power_on(struct phy *phy)

guard(mutex)(&rk_phy->pcie_mutex);

- if (rk_phy->pwr_cnt++) {
- return 0;
- }
-
- err = reset_control_deassert(rk_phy->phy_rst);
+ if (rk_phy->pwr_cnt++)
+ err = reset_control_deassert(rk_phy->phy_rst);
if (err) {
dev_err(&phy->dev, "deassert phy_rst err %d\n", err);
rk_phy->pwr_cnt--;
@@ -181,6 +178,8 @@ static int rockchip_pcie_phy_power_on(struct phy *phy)
HIWORD_UPDATE(!PHY_LANE_IDLE_OFF,
PHY_LANE_IDLE_MASK,
PHY_LANE_IDLE_A_SHIFT + inst->index));
+ if (rk_phy->pwr_cnt)
+ return 0;

/*
* No documented timeout value for phy operation below,