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Date: Wed, 26 Jan 2022 23:12:15 +0800
From: Jisheng Zhang <jszhang@...nel.org>
To: Samuel Holland <samuel@...lland.org>
Cc: Giuseppe Cavallaro <peppe.cavallaro@...com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
Jose Abreu <joabreu@...opsys.com>,
"David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Maxime Ripard <mripard@...nel.org>,
Chen-Yu Tsai <wens@...e.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-sunxi@...ts.linux.dev,
linux-stm32@...md-mailman.stormreply.com,
linux-kernel@...r.kernel.org,
Joakim Zhang <qiangqing.zhang@....com>
Subject: Re: [PATCH] net: stmmac: dwmac-sun8i: fix double disable and
unprepare "stmmaceth" clk
On Sun, Jan 23, 2022 at 01:43:37PM -0600, Samuel Holland wrote:
> On 1/23/22 7:28 AM, Jisheng Zhang wrote:
> > Fix warnings on Allwinner D1 platform:
> >
> > [ 1.604695] ------------[ cut here ]------------
> > [ 1.609328] bus-emac already disabled
> > [ 1.613015] WARNING: CPU: 0 PID: 38 at drivers/clk/clk.c:952 clk_core_disable+0xcc/0xec
> > [ 1.621039] CPU: 0 PID: 38 Comm: kworker/u2:1 Not tainted 5.14.0-rc4#1
> > [ 1.627653] Hardware name: Allwinner D1 NeZha (DT)
> > [ 1.632443] Workqueue: events_unbound deferred_probe_work_func
> > [ 1.638286] epc : clk_core_disable+0xcc/0xec
> > [ 1.642561] ra : clk_core_disable+0xcc/0xec
> > [ 1.646835] epc : ffffffff8023c2ec ra : ffffffff8023c2ec sp : ffffffd00411bb10
> > [ 1.654054] gp : ffffffff80ec9988 tp : ffffffe00143a800 t0 : ffffffff80ed6a6f
> > [ 1.661272] t1 : ffffffff80ed6a60 t2 : 0000000000000000 s0 : ffffffe001509e00
> > [ 1.668489] s1 : 0000000000000001 a0 : 0000000000000019 a1 : ffffffff80e80bd8
> > [ 1.675707] a2 : 00000000ffffefff a3 : 00000000000000f4 a4 : 0000000000000002
> > [ 1.682924] a5 : 0000000000000001 a6 : 0000000000000030 a7 : 00000000028f5c29
> > [ 1.690141] s2 : 0000000000000800 s3 : ffffffe001375000 s4 : ffffffe01fdf7a80
> > [ 1.697358] s5 : ffffffe001375010 s6 : ffffffff8001fc10 s7 : ffffffffffffffff
> > [ 1.704577] s8 : 0000000000000001 s9 : ffffffff80ecb248 s10: ffffffe001b80000
> > [ 1.711794] s11: ffffffe001b80760 t3 : 0000000000000062 t4 : ffffffffffffffff
> > [ 1.719012] t5 : ffffffff80e0f6d8 t6 : ffffffd00411b8f0
> > [ 1.724321] status: 8000000201800100 badaddr: 0000000000000000 cause: 0000000000000003
> > [ 1.732233] [<ffffffff8023c2ec>] clk_core_disable+0xcc/0xec
> > [ 1.737810] [<ffffffff80240430>] clk_disable+0x38/0x78
> > [ 1.742956] [<ffffffff8001fc0c>] worker_thread+0x1a8/0x4d8
> > [ 1.748451] [<ffffffff8031a500>] stmmac_remove_config_dt+0x1c/0x4c
> > [ 1.754646] [<ffffffff8031c8ec>] sun8i_dwmac_probe+0x378/0x82c
> > [ 1.760484] [<ffffffff8001fc0c>] worker_thread+0x1a8/0x4d8
> > [ 1.765975] [<ffffffff8029a6c8>] platform_probe+0x64/0xf0
> > [ 1.771382] [<ffffffff8029833c>] really_probe.part.0+0x8c/0x30c
> > [ 1.777305] [<ffffffff8029865c>] __driver_probe_device+0xa0/0x148
> > [ 1.783402] [<ffffffff8029873c>] driver_probe_device+0x38/0x138
> > [ 1.789324] [<ffffffff802989cc>] __device_attach_driver+0xd0/0x170
> > [ 1.795508] [<ffffffff802988f8>] __driver_attach_async_helper+0xbc/0xc0
> > [ 1.802125] [<ffffffff802965ac>] bus_for_each_drv+0x68/0xb4
> > [ 1.807701] [<ffffffff80298d1c>] __device_attach+0xd8/0x184
> > [ 1.813277] [<ffffffff802967b0>] bus_probe_device+0x98/0xbc
> > [ 1.818852] [<ffffffff80297904>] deferred_probe_work_func+0x90/0xd4
> > [ 1.825122] [<ffffffff8001f8b8>] process_one_work+0x1e4/0x390
> > [ 1.830872] [<ffffffff8001fd80>] worker_thread+0x31c/0x4d8
> > [ 1.836362] [<ffffffff80026bf4>] kthreadd+0x94/0x188
> > [ 1.841335] [<ffffffff80026bf4>] kthreadd+0x94/0x188
> > [ 1.846304] [<ffffffff8001fa60>] process_one_work+0x38c/0x390
> > [ 1.852054] [<ffffffff80026564>] kthread+0x124/0x160
> > [ 1.857021] [<ffffffff8002643c>] set_kthread_struct+0x5c/0x60
> > [ 1.862770] [<ffffffff80001f08>] ret_from_syscall_rejected+0x8/0xc
> > [ 1.868956] ---[ end trace 8d5c6046255f84a0 ]---
> > [ 1.873675] ------------[ cut here ]------------
> > [ 1.878366] bus-emac already unprepared
> > [ 1.882378] WARNING: CPU: 0 PID: 38 at drivers/clk/clk.c:810 clk_core_unprepare+0xe4/0x168
> > [ 1.890673] CPU: 0 PID: 38 Comm: kworker/u2:1 Tainted: G W 5.14.0-rc4 #1
> > [ 1.898674] Hardware name: Allwinner D1 NeZha (DT)
> > [ 1.903464] Workqueue: events_unbound deferred_probe_work_func
> > [ 1.909305] epc : clk_core_unprepare+0xe4/0x168
> > [ 1.913840] ra : clk_core_unprepare+0xe4/0x168
> > [ 1.918375] epc : ffffffff8023d6cc ra : ffffffff8023d6cc sp : ffffffd00411bb10
> > [ 1.925593] gp : ffffffff80ec9988 tp : ffffffe00143a800 t0 : 0000000000000002
> > [ 1.932811] t1 : ffffffe01f743be0 t2 : 0000000000000040 s0 : ffffffe001509e00
> > [ 1.940029] s1 : 0000000000000001 a0 : 000000000000001b a1 : ffffffe00143a800
> > [ 1.947246] a2 : 0000000000000000 a3 : 00000000000000f4 a4 : 0000000000000001
> > [ 1.954463] a5 : 0000000000000000 a6 : 0000000005fce2a5 a7 : 0000000000000001
> > [ 1.961680] s2 : 0000000000000800 s3 : ffffffff80afeb90 s4 : ffffffe01fdf7a80
> > [ 1.968898] s5 : ffffffe001375010 s6 : ffffffff8001fc10 s7 : ffffffffffffffff
> > [ 1.976115] s8 : 0000000000000001 s9 : ffffffff80ecb248 s10: ffffffe001b80000
> > [ 1.983333] s11: ffffffe001b80760 t3 : ffffffff80b39120 t4 : 0000000000000001
> > [ 1.990550] t5 : 0000000000000000 t6 : ffffffe001600002
> > [ 1.995859] status: 8000000201800120 badaddr: 0000000000000000 cause: 0000000000000003
> > [ 2.003771] [<ffffffff8023d6cc>] clk_core_unprepare+0xe4/0x168
> > [ 2.009609] [<ffffffff802403a0>] clk_unprepare+0x24/0x3c
> > [ 2.014929] [<ffffffff8031a508>] stmmac_remove_config_dt+0x24/0x4c
> > [ 2.021125] [<ffffffff8031c8ec>] sun8i_dwmac_probe+0x378/0x82c
> > [ 2.026965] [<ffffffff8001fc0c>] worker_thread+0x1a8/0x4d8
> > [ 2.032463] [<ffffffff8029a6c8>] platform_probe+0x64/0xf0
> > [ 2.037871] [<ffffffff8029833c>] really_probe.part.0+0x8c/0x30c
> > [ 2.043795] [<ffffffff8029865c>] __driver_probe_device+0xa0/0x148
> > [ 2.049892] [<ffffffff8029873c>] driver_probe_device+0x38/0x138
> > [ 2.055815] [<ffffffff802989cc>] __device_attach_driver+0xd0/0x170
> > [ 2.061999] [<ffffffff802988f8>] __driver_attach_async_helper+0xbc/0xc0
> > [ 2.068616] [<ffffffff802965ac>] bus_for_each_drv+0x68/0xb4
> > [ 2.074193] [<ffffffff80298d1c>] __device_attach+0xd8/0x184
> > [ 2.079769] [<ffffffff802967b0>] bus_probe_device+0x98/0xbc
> > [ 2.085345] [<ffffffff80297904>] deferred_probe_work_func+0x90/0xd4
> > [ 2.091616] [<ffffffff8001f8b8>] process_one_work+0x1e4/0x390
> > [ 2.097367] [<ffffffff8001fd80>] worker_thread+0x31c/0x4d8
> > [ 2.102858] [<ffffffff80026bf4>] kthreadd+0x94/0x188
> > [ 2.107830] [<ffffffff80026bf4>] kthreadd+0x94/0x188
> > [ 2.112800] [<ffffffff8001fa60>] process_one_work+0x38c/0x390
> > [ 2.118551] [<ffffffff80026564>] kthread+0x124/0x160
> > [ 2.123520] [<ffffffff8002643c>] set_kthread_struct+0x5c/0x60
> > [ 2.129268] [<ffffffff80001f08>] ret_from_syscall_rejected+0x8/0xc
> > [ 2.135455] ---[ end trace 8d5c6046255f84a1 ]---
> >
> > the dwmmac-sun8i driver will get the "stmmaceth" clk as tx_clk during
> > driver initialization. If stmmac_dvr_probe() fails due to various
> > reasons, sun8i_dwmac_exit() will disable and unprepare the "stmmaceth"
> > clk, then stmmac_remove_config_dt() will disable and unprepare the
> > clk again.
>
> This should still be balanced, because both stmmac_probe_config_dt and
> sun8i_dwmac_init prepare/enable the clock, so the dwmac-sun8i glue layer calls
> stmmac_dvr_probe with the clock having an enable count of 2. It looks like the
> underlying issue is that commit 5ec55823438e ("net: stmmac: add clocks
> management for gmac driver") introduces unbalanced runtime PM.
I added some printk then retested, the problem is triggered as below:
stmmac_probe_config_dt() enable the clk
sun8i_dwmac_init() enble the clk again
stmmac_dvr_probe() succeed, but it calls pm_runtime_put(), so rpm will
disable the clk
sun8i_dwmac_reset() fails due to various reason
sun8i_dwmac_exit() disable the clk, this is fine
stmmac_remove_config_dt() disable the clk again, so ccf complains.
The key here is: whether we should let stmmac_dvr_probe() calls
pm_runtime_put() or let stmmac users to determine whether we could
let rpm go?
If we keep current behavior: stmmac users need to take care
the code after stmmac_dvr_probe, including error handling code path,
if we touch access registers, we need to call pm_runtime_get_sync()
firstly.
Since the commit 5ec55823438e has been in for a long time, I'll submit
a patch to follow this way.
Thanks
> - stmmac_dvr_probe calls pm_runtime_get_noresume and pm_runtime_set_active,
> since it assumes the clocks are already enabled. This is fine.
> - If stmmac_dvr_probe fails, it calls stmmac_bus_clks_config(priv, false),
> which drops the enable count down to 1. This is a bug, not just in this case,
> but also because it will unbalance the clocks if runtime PM is disabled.
> - If stmmac_dvr_probe fails, it never calls pm_runtime_disable if the failure
> occurs after the call to pm_runtime_enable. This is also a bug.
>
> It looks like at some point stmmac_dvr_remove was expected to leave all of the
> clocks disabled, but it must leave them enabled as of commit 8f269102baf7 ("net:
> stmmac: disable clocks in stmmac_remove_config_dt()"), since
> stmmac_remove_config_dt is called after stmmac_dvr_remove in stmmac_pltfr_remove.
> - If stmmac_dvr_probe succeeds, it calls pm_runtime_put. This allows runtime PM
> to suspend the device, dropping the clock enable count to 1. This is fine.
> - But then stmmac_dvr_remove calls pm_runtime_put as well. It needs to do the
> opposite. It must ensure the device is runtime resumed, so the clock enable
> count matches what it was before stmmac_dvr_probe was called (in this case: 2).
>
> > Currently, there's no other usage of tx_clk except preparing and
> > enabling, we can fix the above warnings by simply removing the tx_clk
> > and all its usage, we rely on the common stmmac_probe_config_dt()
> > routine to prepare and enable the stmmaceth clk.
>
> This is a good change to make, as indeed this code is now unnecessary, and
> removing it will allow runtime PM to actually disable the clock. But I am not
> sure how this resolves the warnings you are seeing, as the sun8i_dwmac_init/exit
> calls should have been balanced already.
>
> Can you check if the PHY regulator is also getting unbalanced? Unbalanced calls
> to sun8i_dwmac_exit would also underflow the regulator use count, which should
> trigger its own warning.
>
> Regards,
> Samuel
>
> > Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
> > ---
> > .../net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 20 +------------------
> > 1 file changed, 1 insertion(+), 19 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> > index 617d0e4c6495..d97469825e53 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
> > @@ -57,7 +57,6 @@ struct emac_variant {
> > };
> >
> > /* struct sunxi_priv_data - hold all sunxi private data
> > - * @tx_clk: reference to MAC TX clock
> > * @ephy_clk: reference to the optional EPHY clock for the internal PHY
> > * @regulator: reference to the optional regulator
> > * @rst_ephy: reference to the optional EPHY reset for the internal PHY
> > @@ -68,7 +67,6 @@ struct emac_variant {
> > * @mux_handle: Internal pointer used by mdio-mux lib
> > */
> > struct sunxi_priv_data {
> > - struct clk *tx_clk;
> > struct clk *ephy_clk;
> > struct regulator *regulator;
> > struct reset_control *rst_ephy;
> > @@ -579,22 +577,14 @@ static int sun8i_dwmac_init(struct platform_device *pdev, void *priv)
> > }
> > }
> >
> > - ret = clk_prepare_enable(gmac->tx_clk);
> > - if (ret) {
> > - dev_err(&pdev->dev, "Could not enable AHB clock\n");
> > - goto err_disable_regulator;
> > - }
> > -
> > if (gmac->use_internal_phy) {
> > ret = sun8i_dwmac_power_internal_phy(netdev_priv(ndev));
> > if (ret)
> > - goto err_disable_clk;
> > + goto err_disable_regulator;
> > }
> >
> > return 0;
> >
> > -err_disable_clk:
> > - clk_disable_unprepare(gmac->tx_clk);
> > err_disable_regulator:
> > if (gmac->regulator)
> > regulator_disable(gmac->regulator);
> > @@ -1043,8 +1033,6 @@ static void sun8i_dwmac_exit(struct platform_device *pdev, void *priv)
> > if (gmac->variant->soc_has_internal_phy)
> > sun8i_dwmac_unpower_internal_phy(gmac);
> >
> > - clk_disable_unprepare(gmac->tx_clk);
> > -
> > if (gmac->regulator)
> > regulator_disable(gmac->regulator);
> > }
> > @@ -1167,12 +1155,6 @@ static int sun8i_dwmac_probe(struct platform_device *pdev)
> > return -EINVAL;
> > }
> >
> > - gmac->tx_clk = devm_clk_get(dev, "stmmaceth");
> > - if (IS_ERR(gmac->tx_clk)) {
> > - dev_err(dev, "Could not get TX clock\n");
> > - return PTR_ERR(gmac->tx_clk);
> > - }
> > -
> > /* Optional regulator for PHY */
> > gmac->regulator = devm_regulator_get_optional(dev, "phy");
> > if (IS_ERR(gmac->regulator)) {
> >
>
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