netdev - Re: [PATCH net v3] stmmac: dwmac-mediatek: fix clock issue

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Date:   Tue, 12 Jul 2022 09:10:53 +0800
From:   Biao Huang <biao.huang@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        David Miller <davem@...emloft.net>
CC:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "Eric Dumazet" <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "Paolo Abeni" <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        <netdev@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <macpaul.lin@...iatek.com>
Subject: Re: [PATCH net v3] stmmac: dwmac-mediatek: fix clock issue

Dear Matthias,
	Thanks for your comments.

On Fri, 2022-07-08 at 13:37 +0200, Matthias Brugger wrote:
> Hi Biao Huang,
> 
> On 08/07/2022 11:46, Biao Huang wrote:
> > Dear Mattias,
> > 	Thanks for your comments.
> > 
> > On Fri, 2022-07-08 at 11:22 +0200, Matthias Brugger wrote:
> > > 
> > > On 08/07/2022 10:39, Biao Huang wrote:
> > > > Since clocks are handled in mediatek_dwmac_clks_config(),
> > > > remove the clocks configuration in init()/exit(), and
> > > > invoke mediatek_dwmac_clks_config instead.
> > > > 
> > > > This issue is found in suspend/resume test.
> > > > 
> > > 
> > > Commit message is rather confusing. Basically you are moving the
> > > clock enable
> > > into probe instead of init and remove it from exit. That means,
> > > clocks get
> > > enabled earlier and don't get disabled if the module gets
> > > unloaded.
> > > That doesn't
> > > sound correct, I think we would at least need to disable the
> > > clocks
> > > in remove
> > > function.
> > 
> > there is pm_runtime support in driver, and clocks will be
> > disabled/enabled in stmmac_runtime_suspend/stmmac_runtime_resume.
> > 
> > stmmac_dvr_probe() invoke pm_runtime_put(device) at the end, and
> > disable clocks, but no clock enable at the beginning.
> > so vendor's probe entry should enable clocks to ensure normal
> > behavior.
> > 
> > As to clocks in remove function, we did not test it
> > We should implement a vendor specified remove function who will
> > take
> > care of clocks rather than invoke stmmac_pltfr_remove directly.
> > 
> > Anyway, we miss the clock handling case in remove function,
> > and will
> > test it and feed back.
> 
> Right, sorry I'm not familiar with the stmmac driver stack, yes
> suspend/resume 
> is fine. Thanks for clarification.
> 
> stmmac_pltfr_remove will disable stmmac_clk and pclk but not the rest
> of the 
> clocks. So I think you will need to have specific remove function to
> disable them.
Yes, I'll rewrite the commit message and test remove function,
if need any modification, will add them in next send.

Best Regards!
Biao
> 
> > > 
> > > I suppose that suspend calls exit and that there was a problem
> > > when
> > > we disable
> > > the clocks there. Is this a HW issue that has no other possible
> > > fix?
> > 
> > Not a HW issue. suspend/resume will disable/enable clocks by
> > invoking
> > stmmac_pltfr_noirq_suspend/stmmac_pltfr_noirq_resume -->
> > pm_runtime_force_suspend/pm_runtime_force_resume-->
> > mediatek_dwmac_clks_config, so old clock handling in init/exit is
> > no
> > longer a proper choice.
> > 
> 
> Got it, thanks for clarification.
> 
> Best regards,
> Matthias
> 
> > Best Regards!
> > Biao
> > 
> > > 
> > > Regards,
> > > Matthias
> > > 
> > > > Fixes: 3186bdad97d5 ("stmmac: dwmac-mediatek: add platform
> > > > level
> > > > clocks management")
> > > > Signed-off-by: Biao Huang <biao.huang@...iatek.com>
> > > > ---
> > > >    .../ethernet/stmicro/stmmac/dwmac-mediatek.c  | 36 +++++--
> > > > -------
> > > > -----
> > > >    1 file changed, 9 insertions(+), 27 deletions(-)
> > > > 
> > > > diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-
> > > > mediatek.c
> > > > b/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
> > > > index 6ff88df58767..e86f3e125cb4 100644
> > > > --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
> > > > +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-mediatek.c
> > > > @@ -576,32 +576,7 @@ static int mediatek_dwmac_init(struct
> > > > platform_device *pdev, void *priv)
> > > >    		}
> > > >    	}
> > > >    
> > > > -	ret = clk_bulk_prepare_enable(variant->num_clks, plat-
> > > > >clks);
> > > > -	if (ret) {
> > > > -		dev_err(plat->dev, "failed to enable clks, err
> > > > = %d\n",
> > > > ret);
> > > > -		return ret;
> > > > -	}
> > > > -
> > > > -	ret = clk_prepare_enable(plat->rmii_internal_clk);
> > > > -	if (ret) {
> > > > -		dev_err(plat->dev, "failed to enable rmii
> > > > internal clk,
> > > > err = %d\n", ret);
> > > > -		goto err_clk;
> > > > -	}
> > > > -
> > > >    	return 0;
> > > > -
> > > > -err_clk:
> > > > -	clk_bulk_disable_unprepare(variant->num_clks, plat-
> > > > >clks);
> > > > -	return ret;
> > > > -}
> > > > -
> > > > -static void mediatek_dwmac_exit(struct platform_device *pdev,
> > > > void
> > > > *priv)
> > > > -{
> > > > -	struct mediatek_dwmac_plat_data *plat = priv;
> > > > -	const struct mediatek_dwmac_variant *variant = plat-
> > > > >variant;
> > > > -
> > > > -	clk_disable_unprepare(plat->rmii_internal_clk);
> > > > -	clk_bulk_disable_unprepare(variant->num_clks, plat-
> > > > >clks);
> > > >    }
> > > >    
> > > >    static int mediatek_dwmac_clks_config(void *priv, bool
> > > > enabled)
> > > > @@ -643,7 +618,6 @@ static int
> > > > mediatek_dwmac_common_data(struct
> > > > platform_device *pdev,
> > > >    	plat->addr64 = priv_plat->variant->dma_bit_mask;
> > > >    	plat->bsp_priv = priv_plat;
> > > >    	plat->init = mediatek_dwmac_init;
> > > > -	plat->exit = mediatek_dwmac_exit;
> > > >    	plat->clks_config = mediatek_dwmac_clks_config;
> > > >    	if (priv_plat->variant->dwmac_fix_mac_speed)
> > > >    		plat->fix_mac_speed = priv_plat->variant-
> > > > > dwmac_fix_mac_speed;
> > > > 
> > > > @@ -712,13 +686,21 @@ static int mediatek_dwmac_probe(struct
> > > > platform_device *pdev)
> > > >    	mediatek_dwmac_common_data(pdev, plat_dat, priv_plat);
> > > >    	mediatek_dwmac_init(pdev, priv_plat);
> > > >    
> > > > +	ret = mediatek_dwmac_clks_config(priv_plat, true);
> > > > +	if (ret)
> > > > +		return ret;
> > > > +
> > > >    	ret = stmmac_dvr_probe(&pdev->dev, plat_dat,
> > > > &stmmac_res);
> > > >    	if (ret) {
> > > >    		stmmac_remove_config_dt(pdev, plat_dat);
> > > > -		return ret;
> > > > +		goto err_drv_probe;
> > > >    	}
> > > >    
> > > >    	return 0;
> > > > +
> > > > +err_drv_probe:
> > > > +	mediatek_dwmac_clks_config(priv_plat, false);
> > > > +	return ret;
> > > >    }
> > > >    
> > > >    static const struct of_device_id mediatek_dwmac_match[] = {