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Date: Mon, 10 Aug 2015 13:35:29 +0530
From: Jassi Brar <jassisinghbrar@...il.com>
To: Moritz Fischer <moritz.fischer@...us.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Rob Herring <robh+dt@...nel.org>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
Michal Simek <michal.simek@...inx.com>,
Sören Brinkmann <soren.brinkmann@...inx.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
mchehab@....samsung.com, Arnd Bergmann <arnd@...db.de>,
joe@...ches.com, jingoohan1@...il.com,
Devicetree List <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCHv7 2/2] mailbox: Adding driver for Xilinx LogiCORE IP mailbox.
On Wed, Jul 15, 2015 at 6:30 AM, Moritz Fischer
<moritz.fischer@...us.com> wrote:
> +
> +static void xilinx_mbox_rx_data(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> + u32 data;
> +
> + if (xilinx_mbox_pending(mbox)) {
> + data = readl_relaxed(mbox->mbox_base + MAILBOX_REG_RDDATA);
> + mbox_chan_received_data(chan, (void *)data);
>
If RDDATA is a FIFO, then above seems wrong - you are assuming
messages are always going to be exactly 32-bits for every protocol.
Ideally you should empty the fifo fully, at least when RX has an
interrupt.
> +
> +static int xilinx_mbox_irq_send_data(struct mbox_chan *chan, void *data)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> + u32 *udata = data;
> +
> + if (xilinx_mbox_full(mbox))
> + return -EBUSY;
>
This check is redundant. last_tx_done already makes sure this is always true.
> + /* enable interrupt before send */
> + xilinx_mbox_tx_intmask(mbox, true);
> +
> + writel_relaxed(*udata, mbox->mbox_base + MAILBOX_REG_WRDATA);
> +
>From status EMPTY and FULL, it seems WRDATA is a FIFO. So here also
you should expect messages to be <= fifo depth. And not assume exactly
32bit messages always.
> +
> +static bool xilinx_mbox_last_tx_done(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + /* return false if mailbox is full */
> + return !xilinx_mbox_full(mbox);
>
Instead of FULL, I think it should check for stricter EMPTY status ...
mbox api submits only 1 message at a time.
> +
> +static bool xilinx_mbox_peek_data(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + return xilinx_mbox_pending(mbox);
> +}
> +
> +static void xilinx_mbox_irq_shutdown(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + /* mask all interrupts */
> + writel_relaxed(0, mbox->mbox_base + MAILBOX_REG_IE);
> +
> + clk_disable_unprepare(mbox->clk);
> +
> + free_irq(mbox->irq, chan);
> +}
> +
> +static void xilinx_mbox_poll_shutdown(struct mbox_chan *chan)
> +{
> + struct xilinx_mbox *mbox = mbox_chan_to_xilinx_mbox(chan);
> +
> + del_timer_sync(&mbox->rxpoll_timer);
> +
> + clk_disable_unprepare(mbox->clk);
> +}
> +
> +static const struct mbox_chan_ops xilinx_mbox_irq_ops = {
> + .send_data = xilinx_mbox_irq_send_data,
> + .startup = xilinx_mbox_irq_startup,
> + .shutdown = xilinx_mbox_irq_shutdown,
> + .last_tx_done = xilinx_mbox_last_tx_done,
> + .peek_data = xilinx_mbox_peek_data,
> +};
> +
> +static const struct mbox_chan_ops xilinx_mbox_poll_ops = {
> + .send_data = xilinx_mbox_poll_send_data,
> + .startup = xilinx_mbox_poll_startup,
> + .shutdown = xilinx_mbox_poll_shutdown,
> + .last_tx_done = xilinx_mbox_last_tx_done,
> + .peek_data = xilinx_mbox_peek_data,
> +};
> +
> +static int xilinx_mbox_probe(struct platform_device *pdev)
> +{
> + struct xilinx_mbox *mbox;
> + struct resource *regs;
> + int ret;
> +
> + mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
> + if (!mbox)
> + return -ENOMEM;
> +
> + /* get clk and enable */
> + mbox->clk = devm_clk_get(&pdev->dev, "mbox");
> + if (IS_ERR(mbox->clk)) {
> + dev_err(&pdev->dev, "Couldn't get clk.\n");
> + return PTR_ERR(mbox->clk);
> + }
> +
> + regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> + mbox->mbox_base = devm_ioremap_resource(&pdev->dev, regs);
> + if (IS_ERR(mbox->mbox_base))
> + return PTR_ERR(mbox->mbox_base);
> +
> + mbox->irq = platform_get_irq(pdev, 0);
> + /* if irq is present, we can use it, otherwise, poll */
> + if (mbox->irq > 0) {
> + mbox->controller.txdone_irq = true;
> + mbox->controller.ops = &xilinx_mbox_irq_ops;
> + } else {
> + dev_info(&pdev->dev, "IRQ not found, fallback to polling.\n");
> + mbox->controller.txdone_poll = true;
> + mbox->controller.txpoll_period = MBOX_POLLING_MS;
> + mbox->controller.ops = &xilinx_mbox_poll_ops;
> +
> + setup_timer(&mbox->rxpoll_timer, xilinx_mbox_poll_rx,
> + (unsigned long)&mbox->chan);
>
I believe there is indeed some platform that doesn't have RX-Interrupt?
If no, please remove this.
If yes, you may want to get some hint from platform about the size of
messages and do mbox_chan_received_data() only upon reading those many
bytes.
Cheers.
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