linux-kernel - Re: [PATCH v4 3/5] firmware: ti_sci: Allocate memory for the LPM modes

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Message-ID: <2558a8fd-68c0-1a3e-61d1-57d032024f5f@ti.com>
Date:   Mon, 21 Nov 2022 23:45:35 +0200
From:   Georgi Vlaev <g-vlaev@...com>
To:     Nishanth Menon <nm@...com>
CC:     Tero Kristo <kristo@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        Vibhore Vardhan <vibhore@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Roger Quadros <rogerq@...nel.org>
Subject: Re: [PATCH v4 3/5] firmware: ti_sci: Allocate memory for the LPM
 modes

Hi Nishanth,

On 11/21/22 20:44, Nishanth Menon wrote:
> On 20:13-20221116, Georgi Vlaev wrote:
> [...]
> 
>> +static int ti_sci_init_suspend(struct platform_device *pdev,
>> +			       struct ti_sci_info *info)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	int ret;
>> +
>> +	dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
>> +	info->ctx_mem_buf = dma_alloc_coherent(info->dev, LPM_CTX_MEM_SIZE,
>> +					       &info->ctx_mem_addr,
>> +					       GFP_KERNEL);
>> +	if (!info->ctx_mem_buf) {
>> +		dev_err(info->dev, "Failed to allocate LPM context memory\n");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	/*
>> +	 * Attempt to call prepare_sleep, this will be NAK'd if suspend is not
>> +	 * supported by firmware in use, in which case we will not attempt to
>> +	 * init suspend.
>> +	 */
>> +	ret = ti_sci_cmd_prepare_sleep(&info->handle, 0,
>> +				       (u32)(info->ctx_mem_addr & 0xffffffff),
>> +				       (u32)((u64)info->ctx_mem_addr >> 32), 0);
>> +
>> +	if (ret)
>> +		goto err;
>> +
>> +	return 0;
>> +err:
>> +	dma_free_coherent(info->dev, LPM_CTX_MEM_SIZE,
>> +			  info->ctx_mem_buf,
>> +			  info->ctx_mem_addr);
>> +	return ret;
>> +}
>> +
>>  /* Description for K2G */
>>  static const struct ti_sci_desc ti_sci_pmmc_k2g_desc = {
>>  	.default_host_id = 2,
>> @@ -3639,6 +3682,14 @@ static int ti_sci_probe(struct platform_device *pdev)
>>  		}
>>  	}
>>  
>> +	ret = ti_sci_init_suspend(pdev, info);
>> +	if (ret)
>> +		dev_warn(dev,
>> +			 "ti_sci_init_suspend failed, mem suspend will be non-functional.\n");
>> +
>> +	/* Suspend is an optional feature, reset return value and continue. */
>> +	ret = 0;
> 
> We end up getting this warning on all platforms with TISCI - even if
> LPM sequence is capable or not - what does the message mean? firmware is
> not capable of supporting sleep or it is a firmware capable of
> supporting, but failed to allocate LPM context memory?
> 
> If it is optional (since it is probing to see if it has functionality),
> then do we need a dev_warn - maybe a softer of form?
> 

Yeah, I agree, the message looks confusing. In both cases we can't enter suspend-to-ram,
but we consider that an optional feature, so a softer message will be more appropriate.


> [...]
> 

-- 
Regards,
Georgi