Re: [PATCH v3 2/3] mailbox: mediatek: add support for adsp mailbox controller

[Tzung-Bi Shih <tzungbi@google.com>]

On Wed, Nov 24, 2021 at 04:45:13PM +0800, allen-kh.cheng wrote:
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index c9fc06c7e685..fc99d9fc80af 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -236,6 +236,13 @@ config MTK_CMDQ_MBOX
>  	  critical time limitation, such as updating display configuration
>  	  during the vblank.
>  
> +config MTK_ADSP_IPC_MBOX
> +	tristate "MediaTek ADSP Mailbox Controller"
> +	depends on ARCH_MEDIATEK || COMPILE_TEST
> +	help
> +	  Say yes here to add support for MediaTek ADSP IPC mailbox controller
> +	  driver. It is used to send short messages between processors with dsp.

Although the file didn't maintain alphabetical order, to be neat, moving MTK_ADSP_IPC_MBOX before MTK_CMDQ_MBOX makes more sense.

> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index c2089f04887e..479a9ae56d5e 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -51,6 +51,8 @@ obj-$(CONFIG_STM32_IPCC) 	+= stm32-ipcc.o
>  
>  obj-$(CONFIG_MTK_CMDQ_MBOX)	+= mtk-cmdq-mailbox.o
>  
> +obj-$(CONFIG_MTK_ADSP_IPC_MBOX)	+= mtk-adsp-mailbox.o
> +

Ditto.  Move CONFIG_MTK_ADSP_IPC_MBOX before CONFIG_MTK_CMDQ_MBOX without blank line separation.

> diff --git a/drivers/mailbox/mtk-adsp-mailbox.c b/drivers/mailbox/mtk-adsp-mailbox.c
[...]
> +static irqreturn_t mtk_adsp_ipc_irq_handler(int irq, void *data)
> +{
> +	struct mbox_chan *ch = (struct mbox_chan *)data;

The cast should be able to remove.

> +static irqreturn_t mtk_adsp_ipc_handler(int irq, void *data)
> +{
> +	struct mbox_chan *ch = (struct mbox_chan *)data;

The cast should be able to remove.

> +static int mtk_adsp_mbox_startup(struct mbox_chan *chan)
> +{
> +	struct adsp_mbox_ch_info *ch_info = chan->con_priv;
> +	void __iomem *reg = ch_info->va_reg;
> +
> +	/* Clear DSP mbox command */
> +	writel(0xFFFFFFFF, reg + MTK_ADSP_MBOX_IN_CMD_CLR);
> +	writel(0xFFFFFFFF, reg + MTK_ADSP_MBOX_OUT_CMD_CLR);
> +
> +	return 0;
> +}
> +
> +static void mtk_adsp_mbox_shutdown(struct mbox_chan *chan)
> +{
> +	chan->con_priv = NULL;
> +}

Shall mtk_adsp_mbox_shutdown() also clear DSP mbox?  I.e.:
writel(0xFFFFFFFF, reg + MTK_ADSP_MBOX_IN_CMD_CLR);
writel(0xFFFFFFFF, reg + MTK_ADSP_MBOX_OUT_CMD_CLR);

> +static int mtk_adsp_mbox_send_data(struct mbox_chan *chan, void *data)
> +{
> +	struct adsp_mbox_ch_info *ch_info = chan->con_priv;
> +	void __iomem *reg = ch_info->va_reg;
> +
> +	spin_lock(&ch_info->lock);
> +	writel(ch_info->ipc_op_val, reg + MTK_ADSP_MBOX_IN_CMD);
> +	spin_unlock(&ch_info->lock);

Why does it need the lock?

Is the write to MTK_ADSP_MBOX_IN_CMD a synchronous operation?
- If yes, I failed to understand why does it need the lock.  Every calls to mtk_adsp_mbox_send_data() should wait for the data transfer completion.
- If no, I also failed to understand why.  mtk_adsp_mbox_send_data() has no way to be aware of the transfer completion.  Would expect a loop for checking the completion for the case.

> +static bool mtk_adsp_mbox_last_tx_done(struct mbox_chan *chan)
> +{
> +	struct adsp_mbox_ch_info *ch_info = chan->con_priv;
> +	void __iomem *reg = ch_info->va_reg;
> +	u32 op = readl(reg + MTK_ADSP_MBOX_IN_CMD);
> +
> +	return (op == 0) ? true : false;

To be concise, return readl(...) == 0;

> +static int mtk_adsp_mbox_probe(struct platform_device *pdev)
> +{
[...]
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "no adsp mbox register resource\n");
> +		return -ENXIO;
> +	}
> +
> +	size = resource_size(res);
> +	priv->va_mboxreg = devm_ioremap(dev, (phys_addr_t)res->start, size);
> +	if (IS_ERR(priv->va_mboxreg))
> +		return PTR_ERR(priv->va_mboxreg);

Use devm_platform_ioremap_resource(), it should be equivalent.

> +	/* set adsp mbox channel info */
> +	ch_info = devm_kzalloc(mbox->dev, sizeof(*ch_info), GFP_KERNEL);

To be neat, use dev instead of mbox->dev.

> +	ret = devm_mbox_controller_register(dev, &priv->mbox);
> +	if (ret < 0)
> +		dev_err(dev, "error: failed to register mailbox:%d\n", ret);
> +
> +	return ret;

To be concise, return devm_mbox_controller_register(...);