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Date: Sun, 11 Nov 2012 10:34:58 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Rob Herring <robherring2@...il.com>
Cc: linaro-dev@...ts.linaro.org, andriy.shevchenko@...el.com,
patches@...aro.org, devicetree-discuss@...ts.ozlabs.org,
spear-devel@...t.st.com, linux-kernel@...r.kernel.org,
rob.herring@...xeda.com
Subject: Re: [PATCH Resend V2] dt: add helper function to read u8 & u16
variables & arrays
Ping!!
On 7 November 2012 09:52, viresh kumar <viresh.kumar@...aro.org> wrote:
> On Tue, Nov 6, 2012 at 7:48 PM, Rob Herring <robherring2@...il.com> wrote:
>>> +#define of_property_read_array(_np, _pname, _out, _sz) \
>
>>> + while (_sz--) \
>>> + *_out++ = (typeof(*_out))be32_to_cpup(_val++); \
>
>> This will not work. You are incrementing _out by 1, 2, or 4 bytes, but
>> _val is always incremented by 4 bytes.
>>
>> According to the dtc commit adding this feature, the values are packed:
>>
>> With this patch the following property assignment:
>>
>> property = /bits/ 16 <0x1234 0x5678 0x0 0xffff>;
>>
>> is equivalent to:
>>
>> property = <0x12345678 0x0000ffff>;
>
> I thought of it a bit more and wasn't actually aligned with your explanation :(
>
> If that is the case, how will current implementation of u32 array will work
> if we pass something like: 0x88 0x84000000 0x5890 from DT?
>
> So, i did a dummy test of my current implementation, with following changes
> in one of my drivers:
>
> dts changes:
>
> cluster0: cluster@0 {
> + data1 = <0x50 0x60 0x70>;
> + data2 = <0x5000 0x6000 0x7000>;
> + data3 = <0x50000000 0x60000000 0x70000000>;
> }
>
> driver changes:
>
> +void test(struct device_node *cluster)
> +{
> + u8 data1[3];
> + u16 data2[3];
> + u32 data3[3], i;
> +
> + of_property_read_u8_array(cluster, "data1", data1, 3);
> + of_property_read_u16_array(cluster, "data2", data2, 3);
> + of_property_read_u32_array(cluster, "data3", data3, 3);
> +
> + for (i = 0; i < 3; i++) {
> + printk(KERN_INFO "u8 %d: %x\n", i, data1[i]);
> + printk(KERN_INFO "u16 %d: %x\n", i, data2[i]);
> + printk(KERN_INFO "u32 %d: %x\n", i, data3[i]);
> + }
> +}
>
> And following is the output
>
> [ 4.087205] u8 0: 50
> [ 4.093746] u16 0: 5000
> [ 4.101067] u32 0: 50000000
> [ 4.109512] u8 1: 60
> [ 4.116036] u16 1: 6000
> [ 4.123357] u32 1: 60000000
> [ 4.131718] u8 2: 70
> [ 4.138241] u16 2: 7000
> [ 4.145573] u32 2: 70000000
>
> which looks to be what we were looking for, isn't it?
>
> Following is fixup for the doc comment missing:
>
> commit 00803aed0781de451048df0d15a3e8c814a343c8
> Author: Viresh Kumar <viresh.kumar@...aro.org>
> Date: Wed Nov 7 09:48:46 2012 +0530
>
> fixup! dt: add helper function to read u8 & u16 variables & arrays
> ---
> drivers/of/base.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index fbb634b..4a6632e 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -669,6 +669,7 @@ EXPORT_SYMBOL(of_find_node_by_phandle);
> * @np: device node from which the property value is to be read.
> * @propname: name of the property to be searched.
> * @out_value: pointer to return value, modified only if return value is 0.
> + * @sz: number of array elements to read
> *
> * Search for a property in a device node and read 8-bit value(s) from
> * it. Returns 0 on success, -EINVAL if the property does not exist,
> @@ -690,6 +691,7 @@ EXPORT_SYMBOL_GPL(of_property_read_u8_array);
> * @np: device node from which the property value is to be read.
> * @propname: name of the property to be searched.
> * @out_value: pointer to return value, modified only if return value is 0.
> + * @sz: number of array elements to read
> *
> * Search for a property in a device node and read 16-bit value(s) from
> * it. Returns 0 on success, -EINVAL if the property does not exist,
> @@ -712,6 +714,7 @@ EXPORT_SYMBOL_GPL(of_property_read_u16_array);
> * @np: device node from which the property value is to be read.
> * @propname: name of the property to be searched.
> * @out_value: pointer to return value, modified only if return value is 0.
> + * @sz: number of array elements to read
> *
> * Search for a property in a device node and read 32-bit value(s) from
> * it. Returns 0 on success, -EINVAL if the property does not exist,
>
> _______________________________________________
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> linaro-dev@...ts.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
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