netdev - RE: [PATCH 2/9] iommu/ipmmu-vmsa: Hook up R8A774E1 DT matching code

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Date:   Thu, 16 Jul 2020 04:42:21 +0000
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
CC:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
        Vinod Koul <vkoul@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Joerg Roedel <joro@...tes.org>,
        Sergei Shtylyov <sergei.shtylyov@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Magnus Damm <magnus.damm@...il.com>,
        dmaengine <dmaengine@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux IOMMU <iommu@...ts.linux-foundation.org>,
        netdev <netdev@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/9] iommu/ipmmu-vmsa: Hook up R8A774E1 DT matching code

Hi Geert-san,

> From: Geert Uytterhoeven, Sent: Tuesday, July 14, 2020 9:40 PM
> 
> Hi Shimoda-san,
> 
> On Tue, Jul 14, 2020 at 1:42 PM Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@...esas.com> wrote:
> > > From: Geert Uytterhoeven, Sent: Tuesday, July 14, 2020 5:42 PM
> > > On Tue, Jul 14, 2020 at 10:30 AM Lad, Prabhakar
> > > <prabhakar.csengg@...il.com> wrote:
> > > > On Tue, Jul 14, 2020 at 9:09 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > > > > On Mon, Jul 13, 2020 at 11:35 PM Lad Prabhakar
> > > > Also the recent patch to add
> > > > "r8a77961" just adds to soc_rcar_gen3_whitelist.
> > >
> > > Oops, commit 17fe16181639801b ("iommu/renesas: Add support for r8a77961")
> > > did it wrong, too.
> >
> > Thank you for the point it out. We should add r8a77961 to the soc_rcar_gen3[].
> > However, I don't know why I could not realize this issue...
> > So, I investigated this a little and then, IIUC, glob_match() which
> > soc_device_match() uses seems to return true, if *pat = "r8a7796" and *str = "r8a77961".
> 
> Are you sure about this?

I'm very sorry. I completely misunderstood the glob_match() behavior.
And, now I understood why the current code can use IPMMU on r8a77961...
# Since the first soc_device_match() will return false, ipmmu_slave_whitelist()
# will return true and then the ipmmu_of_xlate() will be succeeded.

> I enabled CONFIG_GLOB_SELFTEST, and globtest succeeded.
> It does test glob_match("a", "aa"), which is a similar test.
> 
> To be 100% sure, I added:
> 
> --- a/lib/globtest.c
> +++ b/lib/globtest.c
> @@ -59,6 +59,7 @@ static char const glob_tests[] __initconst =
>         "1" "a\0" "a\0"
>         "0" "a\0" "b\0"
>         "0" "a\0" "aa\0"
> +       "0" "r8a7796\0" "r8a77961\0"
>         "0" "a\0" "\0"
>         "1" "\0" "\0"
>         "0" "\0" "a\0"
> 
> and it still succeeded.

I'm very sorry to waste your time about this...

Best regards,
Yoshihiro Shimoda