linux-kernel - Re: [PATCH v2 1/3] ARM: da850: fix infinite loop in clk_set

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Date:   Mon, 5 Dec 2016 10:06:33 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Sekhar Nori <nsekhar@...com>
Cc:     Kevin Hilman <khilman@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Russell King <linux@...linux.org.uk>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        linux-pm <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] ARM: da850: fix infinite loop in clk_set_rate()

2016-12-05 9:38 GMT+01:00 Sekhar Nori <nsekhar@...com>:
> On Friday 02 December 2016 09:08 PM, Bartosz Golaszewski wrote:
>> The aemif clock is added twice to the lookup table in da850.c. This
>> breaks the children list of pll0_sysclk3 as we're using the same list
>> links in struct clk. When calling clk_set_rate(), we get stuck in
>> propagate_rate().
>>
>> Create a separate clock for nand, inheriting the rate of the aemif
>> clock and retrieve it in the davinci_nand module.
>>
>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
>> ---
>>  arch/arm/mach-davinci/da850.c   | 7 ++++++-
>>  drivers/mtd/nand/davinci_nand.c | 2 +-
>>  2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/mach-davinci/da850.c b/arch/arm/mach-davinci/da850.c
>> index e770c97..1fcc986 100644
>> --- a/arch/arm/mach-davinci/da850.c
>> +++ b/arch/arm/mach-davinci/da850.c
>> @@ -367,6 +367,11 @@ static struct clk aemif_clk = {
>>       .flags          = ALWAYS_ENABLED,
>>  };
>>
>> +static struct clk nand_clk = {
>> +     .name           = "nand",
>> +     .parent         = &aemif_clk,
>> +};
>> +
>>  static struct clk usb11_clk = {
>>       .name           = "usb11",
>>       .parent         = &pll0_sysclk4,
>> @@ -537,7 +542,7 @@ static struct clk_lookup da850_clks[] = {
>>       CLK("da830-mmc.0",      NULL,           &mmcsd0_clk),
>>       CLK("da830-mmc.1",      NULL,           &mmcsd1_clk),
>>       CLK("ti-aemif",         NULL,           &aemif_clk),
>> -     CLK(NULL,               "aemif",        &aemif_clk),
>> +     CLK(NULL,               "nand",         &nand_clk),
>
> Why use a NULL device name here?
>
>>       CLK("ohci-da8xx",       "usb11",        &usb11_clk),
>>       CLK("musb-da8xx",       "usb20",        &usb20_clk),
>>       CLK("spi_davinci.0",    NULL,           &spi0_clk),
>> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
>> index 27fa8b8..5857d06 100644
>> --- a/drivers/mtd/nand/davinci_nand.c
>> +++ b/drivers/mtd/nand/davinci_nand.c
>> @@ -694,7 +694,7 @@ static int nand_davinci_probe(struct platform_device *pdev)
>>
>>       ret = -EINVAL;
>>
>> -     info->clk = devm_clk_get(&pdev->dev, "aemif");
>> +     info->clk = devm_clk_get(&pdev->dev, "nand");
>
> This driver is used by keystone devices too. So just changing the
> connection id will likely break them. Why do you need to change the
> connection id?
>
> Thanks,
> Sekhar

Thanks, I didn't know it.

I thought it would make the purpose of the clock more obvious. I'll
change it back to "aemif".

Best regards,
Bartosz Golaszewski