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

[allen-kh.cheng <allen-kh.cheng@mediatek.com>]

Hi Tzung-Bi,
 
Thanks for your suggestions.
 
 
On Wed, 2021-11-24 at 18:25 +0800, Tzung-Bi Shih wrote:
> > 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.
> >
>  

In ADSP MBOX IPC flow,
 
Host would call mbox send data when the shared data transfer completed.
 
(mtk_adsp_mbox_send_data will notice client using MTK_ADSP_MBOX_IN_CMD)
 
It’s more like a signal.
 
In general case,
 
There may be some hosts use the same mbox channel.
 
I think it’s better using lock to protect access to
MTK_ADSP_MBOX_IN_CMD registers
 
 
Thanks,
Allen
 
> > > > +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(...);
>  
>  
>