amba uarts - arm type uarts fifo size provided by device tree

amba uarts - arm type uarts fifo size provided by device tree

[Mark Rutland]

Hi,

Please Cc lakml for patches in this area in future.

On Wed, Feb 18, 2015 at 06:53:11PM +0000, Jorge Ramirez-Ortiz wrote:
> [PATCH 1/2] Documentation: bindings: add optional fifo size property
> [PATCH 2/2] drivers/tty: pl011: read fifo size from OF if present
> 
> 
> These patches aim at resolving an issue present on some of the amba pl011
> uarts.  

Which systems are affected? Neither of your two patches add the property
to any dts file.

> Some of these arm type uarts have their fifo sizes not defined in terms of the
> amba_rev register. 

What does said register actually contain?

Is this a full PL011, or a cut-down SBSA UART?

Mark.

> Those uarts should be able to declare their fifo sizes using the optional
> property "fifo-size" in the device tree. This device tree setting shall take
> precedence over any other values. 
> 
> 
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amba uarts - arm type uarts fifo size provided by device tree

[Jorge Ramirez-Ortiz]

On 02/18/2015 02:06 PM, Mark Rutland wrote:
> Hi,
>
> Please Cc lakml for patches in this area in future.
>
> On Wed, Feb 18, 2015 at 06:53:11PM +0000, Jorge Ramirez-Ortiz wrote:
>> [PATCH 1/2] Documentation: bindings: add optional fifo size property
>> [PATCH 2/2] drivers/tty: pl011: read fifo size from OF if present
>>
>>
>> These patches aim at resolving an issue present on some of the amba pl011
>> uarts.  
> Which systems are affected? Neither of your two patches add the property
> to any dts file.


yes, the system affected is still under revision (I should have mentioned)
https://lkml.org/lkml/2015/2/5/144

this is the board I am using to test
https://www.96boards.org/products/hikey/

>
>> Some of these arm type uarts have their fifo sizes not defined in terms of the
>> amba_rev register. 
> What does said register actually contain?

the amba_rev contains '1' for the Hisilicon Hi6220 SoC

>
> Is this a full PL011, or a cut-down SBSA UART?

I believe is full PL011 (ARM type) - that is what is being run in my tests.

>
> Mark.
>
>> Those uarts should be able to declare their fifo sizes using the optional
>> property "fifo-size" in the device tree. This device tree setting shall take
>> precedence over any other values. 
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe devicetree" in
>> the body of a message to majordomo at vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>

amba uarts - arm type uarts fifo size provided by device tree

[Russell King - ARM Linux]

On Wed, Feb 18, 2015 at 02:33:42PM -0500, Jorge Ramirez-Ortiz wrote:
> On 02/18/2015 02:06 PM, Mark Rutland wrote:
> > Hi,
> >
> > Please Cc lakml for patches in this area in future.
> >
> > On Wed, Feb 18, 2015 at 06:53:11PM +0000, Jorge Ramirez-Ortiz wrote:
> >> [PATCH 1/2] Documentation: bindings: add optional fifo size property
> >> [PATCH 2/2] drivers/tty: pl011: read fifo size from OF if present
> >>
> >>
> >> These patches aim at resolving an issue present on some of the amba pl011
> >> uarts.  
> > Which systems are affected? Neither of your two patches add the property
> > to any dts file.
> 
> 
> yes, the system affected is still under revision (I should have mentioned)
> https://lkml.org/lkml/2015/2/5/144

Sorry, I can't follow that thread.  What FIFO size do your UARTs have?
What is the full ID of the UARTs?

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

amba uarts - arm type uarts fifo size provided by device tree

[Jorge Ramirez-Ortiz]

On 02/18/2015 07:34 PM, Russell King - ARM Linux wrote:
> On Wed, Feb 18, 2015 at 02:33:42PM -0500, Jorge Ramirez-Ortiz wrote:
>> On 02/18/2015 02:06 PM, Mark Rutland wrote:
>>> Hi,
>>>
>>> Please Cc lakml for patches in this area in future.
>>>
>>> On Wed, Feb 18, 2015 at 06:53:11PM +0000, Jorge Ramirez-Ortiz wrote:
>>>> [PATCH 1/2] Documentation: bindings: add optional fifo size property
>>>> [PATCH 2/2] drivers/tty: pl011: read fifo size from OF if present
>>>>
>>>>
>>>> These patches aim at resolving an issue present on some of the amba pl011
>>>> uarts.  
>>> Which systems are affected? Neither of your two patches add the property
>>> to any dts file.
>>
>> yes, the system affected is still under revision (I should have mentioned)
>> https://lkml.org/lkml/2015/2/5/144
> Sorry, I can't follow that thread.  What FIFO size do your UARTs have?
> What is the full ID of the UARTs?
>

I just added a temporary printk to my logs for clarity

[    3.328845] name = f7111000.uart, id = 0x241011, amba_rev = 2, fifo size = 64

[PATCH 2/2] drivers/tty: pl011: read fifo size from OF if present

[Mark Rutland]

On Wed, Feb 18, 2015 at 06:53:13PM +0000, Jorge Ramirez-Ortiz wrote:
> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
> ---
>  drivers/tty/serial/amba-pl011.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 02016fc..23fef63 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -84,6 +84,12 @@ struct vendor_data {
>  
>  static unsigned int get_fifosize_arm(struct amba_device *dev)
>  {
> +	const void *prop;
> +
> +	prop = of_get_property(dev->dev.of_node, "fifo-size", NULL);
> +	if (prop)
> +		return of_read_ulong(prop, 1);

Use of_property_read_u32.

You will need to sanity check the result, also.

What value do you need for your platform?

Mark.

> +
>  	return amba_rev(dev) < 3 ? 16 : 32;
>  }
>  
> -- 
> 1.9.1
> 
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