linux-kernel - Re: [PATCH 02/14] clk: renesas: rzg2l-cpg: Check reset monitor registers

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Date:   Thu, 23 Nov 2023 19:19:19 +0200
From:   claudiu beznea <claudiu.beznea@...on.dev>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     s.shtylyov@....ru, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        linux@...linux.org.uk, geert+renesas@...der.be,
        magnus.damm@...il.com, mturquette@...libre.com, sboyd@...nel.org,
        linus.walleij@...aro.org, p.zabel@...gutronix.de, arnd@...db.de,
        m.szyprowski@...sung.com, alexandre.torgue@...s.st.com, afd@...com,
        broonie@...nel.org, alexander.stein@...tq-group.com,
        eugen.hristev@...labora.com, sergei.shtylyov@...il.com,
        prabhakar.mahadev-lad.rj@...renesas.com,
        biju.das.jz@...renesas.com, linux-renesas-soc@...r.kernel.org,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
        Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 02/14] clk: renesas: rzg2l-cpg: Check reset monitor
 registers



On 23.11.2023 17:53, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Mon, Nov 20, 2023 at 8:01 AM Claudiu <claudiu.beznea@...on.dev> wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>>
>> Hardware manual of both RZ/G2L and RZ/G3S specifies that reset monitor
>> registers need to be interrogated when the reset signals are toggled
>> (chapters "Procedures for Supplying and Stopping Reset Signals" and
>> "Procedure for Activating Modules"). Without this there is a chance that
>> different modules (e.g. Ethernet) to not be ready after reset signal is
>> toggled leading to failures (on probe or resume from deep sleep states).
>>
>> Fixes: ef3c613ccd68 ("clk: renesas: Add CPG core wrapper for RZ/G2L SoC")
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> 
> Thanks for your patch!
> 
>> In case you apply this patch and patch 1/13 as is, please add a Depend-on
>> tag on this patch to point to patch 1/13 for proper backporting.
> 
> There is no such Depend-on tag? Anyway, this patch won't apply if 1/13

typo again... it should have been "Depends-on" which is true, it is not
documented anywhere, but I saw it is used in some commits. Maybe I should
stop using it...

> is not backported...
> 
>> --- a/drivers/clk/renesas/rzg2l-cpg.c
>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
>> @@ -1416,12 +1416,23 @@ static int rzg2l_cpg_assert(struct reset_controller_dev *rcdev,
>>         struct rzg2l_cpg_priv *priv = rcdev_to_priv(rcdev);
>>         const struct rzg2l_cpg_info *info = priv->info;
>>         unsigned int reg = info->resets[id].off;
>> -       u32 value = BIT(info->resets[id].bit) << 16;
>> +       u32 dis = BIT(info->resets[id].bit);
>> +       u32 value = dis << 16;
>> +       int ret = 0;
>>
>>         dev_dbg(rcdev->dev, "assert id:%ld offset:0x%x\n", id, CLK_RST_R(reg));
>>
>>         writel(value, priv->base + CLK_RST_R(reg));
>> -       return 0;
>> +
>> +       if (info->has_clk_mon_regs) {
>> +               ret = readl_poll_timeout_atomic(priv->base + CLK_MRST_R(reg), value,
>> +                                               value & dis, 10, 200);
>> +       } else {
>> +               /* Wait for at least one cycle of the RCLK clock (@ ca. 32 kHz) */
>> +               udelay(35);
>> +       }
> 
> I think this should also take into account CPG_RST_MON on RZ/V2M,
> cfr. rzg2l_cpg_status().

Hm... ok, I'll have a look though it will be a bit difficult to test it ATM.

> 
>> +
>> +       return ret;
>>  }
>>
>>  static int rzg2l_cpg_deassert(struct reset_controller_dev *rcdev,
>> @@ -1432,12 +1443,22 @@ static int rzg2l_cpg_deassert(struct reset_controller_dev *rcdev,
>>         unsigned int reg = info->resets[id].off;
>>         u32 dis = BIT(info->resets[id].bit);
>>         u32 value = (dis << 16) | dis;
>> +       int ret = 0;
>>
>>         dev_dbg(rcdev->dev, "deassert id:%ld offset:0x%x\n", id,
>>                 CLK_RST_R(reg));
>>
>>         writel(value, priv->base + CLK_RST_R(reg));
>> -       return 0;
>> +
>> +       if (info->has_clk_mon_regs) {
>> +               ret = readl_poll_timeout_atomic(priv->base + CLK_MRST_R(reg), value,
>> +                                               !(value & dis), 10, 200);
>> +       } else {
>> +               /* Wait for at least one cycle of the RCLK clock (@ ca. 32 kHz) */
>> +               udelay(35);
>> +       }
> 
> Likewise.
> 
>> +
>> +       return ret;
>>  }
>>
>>  static int rzg2l_cpg_reset(struct reset_controller_dev *rcdev,
> 
> The rest LGTM.
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
>