linux-kernel - Re: [PATCH v2] PCI: mt7621: Sleep a bit after power on the PCIs phy ports

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Date:   Mon, 23 Jan 2023 09:55:20 +0100
From:   Sergio Paracuellos <sergio.paracuellos@...il.com>
To:     linux-pci@...r.kernel.org
Cc:     bhelgaas@...gle.com, lpieralisi@...nel.org, robh@...nel.org,
        kw@...ux.com, matthias.bgg@...il.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] PCI: mt7621: Sleep a bit after power on the PCIs phy ports

Hi!

On Sat, Dec 31, 2022 at 8:40 AM Sergio Paracuellos
<sergio.paracuellos@...il.com> wrote:
>
> Some devices like ZBT WE1326 and ZBT WF3526-P and some Netgear models need
> to sleep a bit after call to mt7621_pcie_init_port() driver function to get
> into reliable boots for both warm and hard resets. The needed time for these
> devices to always detect the ports seems to be from 75 to 100 milliseconds.
> There is no datasheet or something similar to really understand why this
> extra time is needed in these devices but not in most of the boards which
> use mt7621 SoC. This issue has been reported by openWRT community and the
> complete discussion is in [0]. The selected time of 100 milliseconds has
> been also tested in these devices ending up in an always working platform.
> Hence, properly add the extra 100 milliseconds msleep() function call to make
> also these devices work.
>
> [0]: https://github.com/openwrt/openwrt/pull/11220
>
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
> ---
> Hi Bjorn / Lorenzo,
>
> As per Lorenzo comments in v1[0] here it is the patch with changes in commit
> message and introducing a new definition for this needed extra delay time.
> I wish you the best new year for you both.
>
> Changes in v2:
> - Add a new define 'INIT_PORTS_DELAY_MS' avoiding to reuse 'PERST_DELAY_MS'.
> - Rewrite commit message and add a link to openWRT discussion.
>
> Previous patch lore link:
> [0]: https://lore.kernel.org/lkml/20221209071703.2891714-1-sergio.paracuellos@gmail.com/T/
>
> Thanks,
>     Sergio Paracuellos
>
>  drivers/pci/controller/pcie-mt7621.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/pci/controller/pcie-mt7621.c b/drivers/pci/controller/pcie-mt7621.c
> index ee7aad09d627..63a5f4463a9f 100644
> --- a/drivers/pci/controller/pcie-mt7621.c
> +++ b/drivers/pci/controller/pcie-mt7621.c
> @@ -60,6 +60,7 @@
>  #define PCIE_PORT_LINKUP               BIT(0)
>  #define PCIE_PORT_CNT                  3
>
> +#define INIT_PORTS_DELAY_MS            100
>  #define PERST_DELAY_MS                 100
>
>  /**
> @@ -369,6 +370,7 @@ static int mt7621_pcie_init_ports(struct mt7621_pcie *pcie)
>                 }
>         }
>
> +       msleep(INIT_PORTS_DELAY_MS);
>         mt7621_pcie_reset_ep_deassert(pcie);
>
>         tmp = NULL;
> --
> 2.25.1
>

Gentle ping on this patch :-).

Thanks,
    Sergio Paracuellos