linux-kernel - Re: [PATCH] MIPS: Revert "add support for buggy MT7621S core detection"

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Date:   Thu, 30 Sep 2021 19:14:00 +0200
From:   Sergio Paracuellos <sergio.paracuellos@...il.com>
To:     Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "open list:MIPS" <linux-mips@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Greg Ungerer <gerg@...nel.org>,
        Strontium <strntydog@...il.com>,
        "Maciej W. Rozycki" <macro@...am.me.uk>,
        Felix Fietkau <nbd@....name>
Subject: Re: [PATCH] MIPS: Revert "add support for buggy MT7621S core detection"

On Thu, Sep 30, 2021 at 6:58 PM Ilya Lipnitskiy
<ilya.lipnitskiy@...il.com> wrote:
>
> This reverts commit 6decd1aad15f56b169217789630a0098b496de0e. CPULAUNCH
> register is not set properly by some bootloaders, causing a regression
> until a bootloader change is made, which is hard if not impossible on
> some embedded devices. Revert the change until a more robust core
> detection mechanism that works on MT7621S routers such as Netgear R6220
> as well as platforms like Digi EX15 can be made.
>
> Link: https://lore.kernel.org/lkml/4d9e3b39-7caa-d372-5d7b-42dcec36fec7@kernel.org
> Fixes: 6decd1aad15f ("MIPS: add support for buggy MT7621S core detection")
> Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>
> ---
>  arch/mips/include/asm/mips-cps.h | 23 +----------------------
>  1 file changed, 1 insertion(+), 22 deletions(-)

Acked-by: Sergio Paracuellos <sergio.paracuellos@...il.com>

Thanks,
     Sergio Paracuellos
>
> diff --git a/arch/mips/include/asm/mips-cps.h b/arch/mips/include/asm/mips-cps.h
> index 35fb8ee6dd33..fd43d876892e 100644
> --- a/arch/mips/include/asm/mips-cps.h
> +++ b/arch/mips/include/asm/mips-cps.h
> @@ -10,8 +10,6 @@
>  #include <linux/io.h>
>  #include <linux/types.h>
>
> -#include <asm/mips-boards/launch.h>
> -
>  extern unsigned long __cps_access_bad_size(void)
>         __compiletime_error("Bad size for CPS accessor");
>
> @@ -167,30 +165,11 @@ static inline uint64_t mips_cps_cluster_config(unsigned int cluster)
>   */
>  static inline unsigned int mips_cps_numcores(unsigned int cluster)
>  {
> -       unsigned int ncores;
> -
>         if (!mips_cm_present())
>                 return 0;
>
>         /* Add one before masking to handle 0xff indicating no cores */
> -       ncores = (mips_cps_cluster_config(cluster) + 1) & CM_GCR_CONFIG_PCORES;
> -
> -       if (IS_ENABLED(CONFIG_SOC_MT7621)) {
> -               struct cpulaunch *launch;
> -
> -               /*
> -                * Ralink MT7621S SoC is single core, but the GCR_CONFIG method
> -                * always reports 2 cores. Check the second core's LAUNCH_FREADY
> -                * flag to detect if the second core is missing. This method
> -                * only works before the core has been started.
> -                */
> -               launch = (struct cpulaunch *)CKSEG0ADDR(CPULAUNCH);
> -               launch += 2; /* MT7621 has 2 VPEs per core */
> -               if (!(launch->flags & LAUNCH_FREADY))
> -                       ncores = 1;
> -       }
> -
> -       return ncores;
> +       return (mips_cps_cluster_config(cluster) + 1) & CM_GCR_CONFIG_PCORES;
>  }
>
>  /**
> --
> 2.33.0
>