linux-kernel - Re: [PATCH] Revert "clk: imx: fix composite peripheral flags"

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Message-ID: <CAOMZO5Bq5Qs90iZQTpouv5wW_xf0CQcP-i-+c-Jp-_Ftvhknnw@mail.gmail.com>
Date:   Thu, 31 Dec 2020 17:33:40 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Martin Kepplinger <martin.kepplinger@...i.sm>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        linux-clk <linux-clk@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Revert "clk: imx: fix composite peripheral flags"

Hi Martin,

On Thu, Dec 31, 2020 at 11:22 AM Martin Kepplinger
<martin.kepplinger@...i.sm> wrote:
>
> This reverts commit 936c383673b9e3007432f17140ac62de53d87db9.
>
> It breaks clock reparenting via devfreq on the imx8mq used in the
> Librem 5 phone. When switching dram frequency (which worked before)
> the system now hangs after this where the dram_apb clock cannot be
> set:
>
> [  129.391755] imx8m-ddrc-devfreq 3d400000.memory-controller: failed to
> set dram_apb parent: -16
> [  129.391959] imx8m-ddrc-devfreq 3d400000.memory-controller: ddrc
> failed freq switch to 25000000 from 800000000: error -16. now at 25000000
> [  129.406133] imx8m-ddrc-devfreq 3d400000.memory-controller: failed to
> update frequency from PM QoS (-16)

I am wondering whether IMX8MQ_CLK_DRAM_ALT should also be marked as
CLK_IS_CRITICAL.

Could you please try the following change without the revert?

--- a/drivers/clk/imx/clk-imx8mq.c
+++ b/drivers/clk/imx/clk-imx8mq.c
@@ -458,7 +458,7 @@ static int imx8mq_clocks_probe(struct platform_device *pdev)
         * Mark with GET_RATE_NOCACHE to always read div value from hardware
         */
        hws[IMX8MQ_CLK_DRAM_CORE] =
imx_clk_hw_mux2_flags("dram_core_clk", base + 0x9800, 24, 1,
imx8mq_dram_core_sels, ARRAY_SIZE(imx8mq_dram_core_sels),
CLK_IS_CRITICAL);
-       hws[IMX8MQ_CLK_DRAM_ALT] =
__imx8m_clk_hw_composite("dram_alt", imx8mq_dram_alt_sels, base +
0xa000, CLK_GET_RATE_NOCACHE);
+       hws[IMX8MQ_CLK_DRAM_ALT] =
__imx8m_clk_hw_composite("dram_alt", imx8mq_dram_alt_sels, base +
0xa000, CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE);
        hws[IMX8MQ_CLK_DRAM_APB] =
__imx8m_clk_hw_composite("dram_apb", imx8mq_dram_apb_sels, base +
0xa080, CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE);

Thanks