Re: [PATCH v4 5/6] PCI: mediatek-gen3: Add reset delay in mtk_pcie_en7581_power_up()

[Lorenzo Bianconi <lorenzo@kernel.org>]

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> On Mon, Nov 18, 2024 at 09:04:57AM +0100, Lorenzo Bianconi wrote:
> > Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal
> > causing occasional PCIe link down issues. In order to overcome the
> > problem, PCIe block is reset using REG_PCI_CONTROL (0x88) and
> > REG_RESET_CONTROL (0x834) registers available in the clock module
> > running clk_bulk_prepare_enable in mtk_pcie_en7581_power_up().
> > In order to make the code more readable, move the wait for the time
> > needed to complete the PCIe reset from en7581_pci_enable() to
> > mtk_pcie_en7581_power_up().
> > Reduce reset timeout from 250ms to PCIE_T_PVPERL_MS (100ms).
> > 
> 
> and this reduced timeout has no impact on the behavior? If so, it'd be good to
> state it explicitly. But this information can be added while applying the patch,
> so no need to resend just for this.

nope, we discussed this here:
https://patchwork.kernel.org/project/linux-pci/patch/aca00bd672ee576ad96d279414fc0835ff31f637.1720022580.git.lorenzo@kernel.org/#26114968

no worries, I will fix it in v5 since I need to repost to address a
comment in patch 3/6.

Regards,
Lorenzo

> 
> > Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> > Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> 
> - Mani
> 
> > ---
> >  drivers/clk/clk-en7523.c                    | 1 -
> >  drivers/pci/controller/pcie-mediatek-gen3.c | 7 +++++++
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/clk/clk-en7523.c b/drivers/clk/clk-en7523.c
> > index 22fbea61c3dcc05e63f8fa37e203c62b2a6fe79e..bf9d9594bef8a54316e28e56a1642ecb0562377a 100644
> > --- a/drivers/clk/clk-en7523.c
> > +++ b/drivers/clk/clk-en7523.c
> > @@ -393,7 +393,6 @@ static int en7581_pci_enable(struct clk_hw *hw)
> >  	       REG_PCI_CONTROL_PERSTOUT;
> >  	val = readl(np_base + REG_PCI_CONTROL);
> >  	writel(val | mask, np_base + REG_PCI_CONTROL);
> > -	msleep(250);
> >  
> >  	return 0;
> >  }
> > diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> > index e4f890a73cb8ada7423301fa7a9acc3e177d0cad..f47c0f2995d94ea99bf41146657bd90b87781a7c 100644
> > --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> > +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> > @@ -980,6 +980,13 @@ static int mtk_pcie_en7581_power_up(struct mtk_gen3_pcie *pcie)
> >  		goto err_clk_prepare_enable;
> >  	}
> >  
> > +	/*
> > +	 * Airoha EN7581 performs PCIe reset via clk callabacks since it has a
> > +	 * hw issue with PCIE_PE_RSTB signal. Add wait for the time needed to
> > +	 * complete the PCIe reset.
> > +	 */
> > +	msleep(PCIE_T_PVPERL_MS);
> > +
> >  	return 0;
> >  
> >  err_clk_prepare_enable:
> > 
> > -- 
> > 2.47.0
> > 
> 
> -- 
> மணிவண்ணன் சதாசிவம்

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