[PATCH v3 1/3] ARM: da850: fix infinite loop in clk_set_rate()

[nsekhar@ti.com (Sekhar Nori)]

On Tuesday 06 December 2016 05:28 PM, Bartosz Golaszewski wrote:
> 2016-12-05 11:15 GMT+01:00 Sekhar Nori <nsekhar@ti.com>:
>> On Monday 05 December 2016 03:39 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@baylibre.com>
>>> ---
>>>  arch/arm/mach-davinci/da850.c | 7 ++++++-
>>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/mach-davinci/da850.c b/arch/arm/mach-davinci/da850.c
>>> index e770c97..c008e5e 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 aemif_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,               "aemif",        &aemif_nand_clk),
>>
>> Why use a NULL device name here?
> 
> Hi Sekhar,
> 
> there's an issue with this bit. I added an of_dev_auxdata entry to
> da8xx-dt.c for the nand node, but it didn't work (the nand driver
> could not get the clock). When I dug deeper, it turned out, the nand
> node is created from aemif_probe() instead of from
> da850_init_machine() and the lookup table is not passed as argument to
> of_platform_populate().
> 
> There are two solutions: one is using "620000000.nand" as dev_id in
> the clock lookup table, but that's ugly. The second is leaving dev_id
> as NULL - I verified that the nand driver works correctly having only
> the connector id. Please let me know which one you prefer or if you
> have other ideas.

Alright, I will take a look at whats going on here. This series will
have to wait for v4.11 anyway.

Thanks,
Sekhar