Re: [PATCH 1/1] mmc: mmci: add threaded irq to abort DPSM of non-functional state
From: Ulf Hansson <hidden>
Date: 2019-11-14 15:10:01
Also in:
linux-devicetree, linux-mmc, lkml
On Wed, 13 Nov 2019 at 18:25, Ludovic Barre [off-list ref] wrote:
From: Ludovic Barre <redacted> If datatimeout occurs on R1B request, the Data Path State Machine stays in busy and is non-functional. Only a reset aborts the DPSM.
Please clarify/extend this information to tell that this is for the variant, that keeps DPSM enabled and uses the data timer while sending a CMD12. Or something along those lines.
Like a reset must be outside of critical section, this patch adds
/s/critical section/atomic context
quoted hunk ↗ jump to hunk
threaded irq function to release state machine. In this case, the mmc_request_done is called at the end of threaded irq and skipped into irq handler. Signed-off-by: Ludovic Barre <redacted> --- drivers/mmc/host/mmci.c | 44 ++++++++++++++++++++++++++++++++++++----- drivers/mmc/host/mmci.h | 1 + 2 files changed, 40 insertions(+), 5 deletions(-)diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index 40e72c30ea84..ec6e249c87ca 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c@@ -556,6 +556,9 @@ static void mmci_dma_error(struct mmci_host *host) static void mmci_request_end(struct mmci_host *host, struct mmc_request *mrq) { + if (host->irq_action == IRQ_WAKE_THREAD) + return; + writel(0, host->base + MMCICOMMAND); BUG_ON(host->data);@@ -1321,6 +1324,7 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd, } else if (host->variant->busy_timeout && busy_resp && status & MCI_DATATIMEOUT) { cmd->error = -ETIMEDOUT; + host->irq_action = IRQ_WAKE_THREAD; } else { cmd->resp[0] = readl(base + MMCIRESPONSE0); cmd->resp[1] = readl(base + MMCIRESPONSE1);@@ -1532,9 +1536,9 @@ static irqreturn_t mmci_irq(int irq, void *dev_id) { struct mmci_host *host = dev_id; u32 status; - int ret = 0; spin_lock(&host->lock); + host->irq_action = IRQ_HANDLED; do { status = readl(host->base + MMCISTATUS);@@ -1574,12 +1578,41 @@ static irqreturn_t mmci_irq(int irq, void *dev_id) if (host->variant->busy_detect_flag) status &= ~host->variant->busy_detect_flag; - ret = 1; } while (status); spin_unlock(&host->lock); - return IRQ_RETVAL(ret); + return host->irq_action; +} + +/* + * mmci_irq_threaded is call if the mmci host need to release state machines + * before to terminate the request. + * If datatimeout occurs on R1B request, the Data Path State Machine stays + * in busy and is non-functional. Only a reset can to abort the DPSM. + */ +static irqreturn_t mmci_irq_threaded(int irq, void *dev_id) +{ + struct mmci_host *host = dev_id; + unsigned long flags; + + if (host->rst) { + reset_control_assert(host->rst); + udelay(2); + reset_control_deassert(host->rst); + } + + spin_lock_irqsave(&host->lock, flags); + writel(host->clk_reg, host->base + MMCICLOCK); + writel(host->pwr_reg, host->base + MMCIPOWER); + writel(MCI_IRQENABLE | host->variant->start_err, + host->base + MMCIMASK0); + + host->irq_action = IRQ_HANDLED; + mmci_request_end(host, host->mrq); + spin_unlock_irqrestore(&host->lock, flags); + + return host->irq_action; } static void mmci_request(struct mmc_host *mmc, struct mmc_request *mrq)@@ -2071,8 +2104,9 @@ static int mmci_probe(struct amba_device *dev, goto clk_disable; } - ret = devm_request_irq(&dev->dev, dev->irq[0], mmci_irq, IRQF_SHARED, - DRIVER_NAME " (cmd)", host); + ret = devm_request_threaded_irq(&dev->dev, dev->irq[0], mmci_irq, + mmci_irq_threaded, IRQF_SHARED, + DRIVER_NAME " (cmd)", host);
In general it's a good idea to move drivers into using a threaded IRQ handler. However, the reason this hasn't been done for mmci before, is because there are some legacy variants, that doesn't support HW flow control. Unless I am mistaken, that means when the fifo gets full during data transfers - it's too late to act. In other words, running the handler in hard IRQ context, should increase the probability of not missing the deadline. If a threaded IRQ handler also is sufficient for these legacy variants, only tests can tell. An option, would be to use a threaded handler for those variants that supports HW flow control. Not sure how messy the code would be with this option, perhaps you can give this a try?
quoted hunk ↗ jump to hunk
if (ret) goto clk_disable;diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h index 158e1231aa23..5e63c0596364 100644 --- a/drivers/mmc/host/mmci.h +++ b/drivers/mmc/host/mmci.h@@ -412,6 +412,7 @@ struct mmci_host { struct timer_list timer; unsigned int oldstat; + u32 irq_action; /* pio stuff */ struct sg_mapping_iter sg_miter; --2.17.1
Kind regards Uffe _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel