linux-kernel - Re: [PATCH 1/3] ARM: davinci: da8xx: Create DSP device only when assigned memory

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Date:   Mon, 22 May 2017 14:49:29 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Suman Anna <s-anna@...com>, Kevin Hilman <khilman@...nel.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] ARM: davinci: da8xx: Create DSP device only when
 assigned memory

On Thursday 18 May 2017 09:29 PM, Suman Anna wrote:
> Hi Sekhar,
> 
> On 05/18/2017 01:10 AM, Sekhar Nori wrote:
>> On Wednesday 17 May 2017 03:43 AM, Suman Anna wrote:
>>> The DSP device on Davinci platforms does not have an MMU and requires
>>> specific DDR memory to boot. This memory is reserved using the rproc_mem
>>> kernel boot parameter and is assigned to the device on non-DT boots.
>>> The remoteproc core uses the DMA API and so will fall back to assigning
>>> random memory if this memory is not assigned to the device, but the DSP
>>> remote processor boot will not be successful in such cases. So, check
>>> that memory has been reserved and assigned to the device specifically
>>> before even creating the DSP device.
>>>
>>> Signed-off-by: Suman Anna <s-anna@...com>
>>> ---
>>>  arch/arm/mach-davinci/devices-da8xx.c | 10 ++++++++++
>>>  1 file changed, 10 insertions(+)
>>>
>>> diff --git a/arch/arm/mach-davinci/devices-da8xx.c b/arch/arm/mach-davinci/devices-da8xx.c
>>> index 7cf529ffbe5a..1ccf52e49886 100644
>>> --- a/arch/arm/mach-davinci/devices-da8xx.c
>>> +++ b/arch/arm/mach-davinci/devices-da8xx.c
>>> @@ -814,6 +814,8 @@ static struct platform_device da8xx_dsp = {
>>>  	.resource	= da8xx_rproc_resources,
>>>  };
>>>  
>>> +static bool rproc_mem_inited __initdata;
>>> +
>>>  #if IS_ENABLED(CONFIG_DA8XX_REMOTEPROC)
>>>  
>>>  static phys_addr_t rproc_base __initdata;
>>> @@ -852,6 +854,8 @@ void __init da8xx_rproc_reserve_cma(void)
>>>  	ret = dma_declare_contiguous(&da8xx_dsp.dev, rproc_size, rproc_base, 0);
>>>  	if (ret)
>>>  		pr_err("%s: dma_declare_contiguous failed %d\n", __func__, ret);
>>> +	else
>>> +		rproc_mem_inited = true;
>>>  }
>>>  
>>>  #else
>>> @@ -866,6 +870,12 @@ int __init da8xx_register_rproc(void)
>>>  {
>>>  	int ret;
>>>  
>>> +	if (!rproc_mem_inited) {
>>> +		pr_warn("%s: memory not reserved for DSP, not registering DSP device\n",
>>> +			__func__);
>>
>> We now have a warning and an error if dma_declare_contiguous() fails. I
>> like this message better. So can you replace the existing error message
>> with this text instead ?
> 
> Hmm, this trace is not just covering the dma_declare_contiguous failure.
> There can be two different errors in da8xx_rproc_reserve_cma, and this

I seem to have missed that part. I now applied this series to v4.13/soc.
I don't have a branch in linux-next. So, it may be a while before it
ends up there. But I do merge all the patches I apply to master branch
of my tree.

Thanks,
Sekhar