linux-kernel - Re: [PATCH] ASoC: SOF: mediatek: mt8186 modify dram type as non-cache

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Date:   Thu, 3 Aug 2023 11:04:03 +0300
From:   Eugen Hristev <eugen.hristev@...labora.com>
To:     Trevor Wu <trevor.wu@...iatek.com>,
        pierre-louis.bossart@...ux.intel.com,
        peter.ujfalusi@...ux.intel.com, yung-chuan.liao@...ux.intel.com,
        ranjani.sridharan@...ux.intel.com, kai.vehmanen@...ux.intel.com,
        daniel.baluta@....com, broonie@...nel.org, lgirdwood@...il.com,
        tiwai@...e.com, perex@...ex.cz, matthias.bgg@...il.com,
        angelogioacchino.delregno@...labora.com
Cc:     yc.hung@...iatek.com, allen-kh.cheng@...iatek.com,
        sound-open-firmware@...a-project.org, alsa-devel@...a-project.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: SOF: mediatek: mt8186 modify dram type as non-cache

Hi Trevor,

On 8/3/23 10:50, Trevor Wu wrote:
> To prevent incorrect access between the host and DSP sides, we need to
> modify DRAM as a non-cache memory type. Additionally, we can retrieve
> the size of shared DMA from the device tree.
> 
> Signed-off-by: Trevor Wu <trevor.wu@...iatek.com>
> Reviewed-by: Yaochun Hung <yc.hung@...iatek.com>
> Reviewed-by: Kuan-Hsun Cheng <Allen-KH.Cheng@...iatek.com>
> ---
>   sound/soc/sof/mediatek/mt8186/mt8186.c | 40 +++++++++++++++-----------
>   1 file changed, 23 insertions(+), 17 deletions(-)
> 
> diff --git a/sound/soc/sof/mediatek/mt8186/mt8186.c b/sound/soc/sof/mediatek/mt8186/mt8186.c
> index 3e0ea0e109e2..f587edf9e0a7 100644
> --- a/sound/soc/sof/mediatek/mt8186/mt8186.c
> +++ b/sound/soc/sof/mediatek/mt8186/mt8186.c
> @@ -111,6 +111,14 @@ static int platform_parse_resource(struct platform_device *pdev, void *data)
>   
>   	dev_dbg(dev, "DMA %pR\n", &res);
>   
> +	adsp->pa_shared_dram = (phys_addr_t)res.start;
> +	adsp->shared_size = resource_size(&res);
> +	if (adsp->pa_shared_dram & DRAM_REMAP_MASK) {
> +		dev_err(dev, "adsp shared dma memory(%#x) is not 4K-aligned\n",
> +			(u32)adsp->pa_shared_dram);
> +		return -EINVAL;
> +	}
> +

Would it be better to just realign to the next 4k boundary ?
Or, isn't it more usual to use dma_coerce_mask_and_coherent ?

>   	ret = of_reserved_mem_device_init(dev);
>   	if (ret) {
>   		dev_err(dev, "of_reserved_mem_device_init failed\n");
> @@ -244,23 +252,18 @@ static int adsp_shared_base_ioremap(struct platform_device *pdev, void *data)
>   {
>   	struct device *dev = &pdev->dev;
>   	struct mtk_adsp_chip_info *adsp = data;
> -	u32 shared_size;
>   
>   	/* remap shared-dram base to be non-cachable */
> -	shared_size = TOTAL_SIZE_SHARED_DRAM_FROM_TAIL;
> -	adsp->pa_shared_dram = adsp->pa_dram + adsp->dramsize - shared_size;
> -	if (adsp->va_dram) {
> -		adsp->shared_dram = adsp->va_dram + DSP_DRAM_SIZE - shared_size;
> -	} else {
> -		adsp->shared_dram = devm_ioremap(dev, adsp->pa_shared_dram,
> -						 shared_size);
> -		if (!adsp->shared_dram) {
> -			dev_err(dev, "ioremap failed for shared DRAM\n");
> -			return -ENOMEM;
> -		}
> +	adsp->shared_dram = devm_ioremap(dev, adsp->pa_shared_dram,
> +					 adsp->shared_size);

You cannot use dma_alloc_coherent ? This should take care of all the 
cache maintainance for you.

> +	if (!adsp->shared_dram) {
> +		dev_err(dev, "failed to ioremap base %pa size %#x\n",
> +			adsp->shared_dram, adsp->shared_size);
> +		return -ENOMEM;
>   	}
> -	dev_dbg(dev, "shared-dram vbase=%p, phy addr :%pa, size=%#x\n",
> -		adsp->shared_dram, &adsp->pa_shared_dram, shared_size);
> +
> +	dev_dbg(dev, "shared-dram vbase=%p, phy addr :%pa,  size=%#x\n",
> +		adsp->shared_dram, &adsp->pa_shared_dram, adsp->shared_size);
>   
>   	return 0;
>   }
> @@ -307,9 +310,12 @@ static int mt8186_dsp_probe(struct snd_sof_dev *sdev)
>   		return -ENOMEM;
>   	}
>   
> -	sdev->bar[SOF_FW_BLK_TYPE_SRAM] = devm_ioremap_wc(sdev->dev,
> -							  priv->adsp->pa_dram,
> -							  priv->adsp->dramsize);
> +	priv->adsp->va_sram = sdev->bar[SOF_FW_BLK_TYPE_IRAM];
> +
> +	sdev->bar[SOF_FW_BLK_TYPE_SRAM] = devm_ioremap(sdev->dev,
> +						       priv->adsp->pa_dram,
> +						       priv->adsp->dramsize);
> +
Same here

>   	if (!sdev->bar[SOF_FW_BLK_TYPE_SRAM]) {
>   		dev_err(sdev->dev, "failed to ioremap base %pa size %#x\n",
>   			&priv->adsp->pa_dram, priv->adsp->dramsize);


Regards,
Eugen