linux-kernel - Re: [PATCH] clk: imx25: set correct parents for ssi ipg clocks

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Date:   Thu, 8 Mar 2018 15:08:51 +0100
From:   Martin Kaiser <martin@...ser.cx>
To:     Fabio Estevam <festevam@...il.com>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <fabio.estevam@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: imx25: set correct parents for ssi ipg clocks

Hi Fabio,

Thus wrote Fabio Estevam (festevam@...il.com):

> I get audio working from SSI1, but I guess this is due to the fact
> that the bootloader enables the SSI clock:

> I have the following in U-Boot:

> /* Enable the clocks */
> DATA 4 0x53f8000c 0x1fffffff
> DATA 4 0x53f80010 0xffffffff
> DATA 4 0x53f80014 0xfdfff

I'm using the same initial settings.

Nevertheless, ssi1_ipg_per is disbled after loading the kernel.

Digging into this a bit more, it turned out that without my patch,
clk_disable_unused() recognizes ssi1_ipg_per as unused and disables it.

If my patch is applied and ssi1_ipg_per is declared as parent of
ssi1_ipg, clk_disable_unused() will not disable it and fsl_ssi_startup()
will enable both ssi1_ipg_per and ssi1_ipg before playing sound.

Best regards,
Martin