Re: [PATCH v2 2/2] usb: dwc2: host: Clear interrupts before handling them

John Youn
2015-11-05T03:09:04Z

On 11/3/2015 12:31 PM, Douglas Anderson wrote:
> In general it is wise to clear interrupts before processing them. If
> you don't do that, you can get:
> 1. Interrupt happens
> 2. You look at system state and process interrupt
> 3. A new interrupt happens
> 4. You clear interrupt without processing it.
>
> This patch was actually a first attempt to fix missing device insertions
> as described in (usb: dwc2: host: Fix missing device insertions) and it
> did solve some of the signal bouncing problems but not all of
> them (which is why I submitted the other patch). Specifically, this
> patch itself would sometimes change:
> 1. hardware sees connect
> 2. hardware sees disconnect
> 3. hardware sees connect
> 4. dwc2_port_intr() - clears connect interrupt
> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>
> ...to:
> 1. hardware sees connect
> 2. hardware sees disconnect
> 3. dwc2_port_intr() - clears connect interrupt
> 4. hardware sees connect
> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>
> ...but with different timing then sometimes we'd still miss cable
> insertions.
>
> In any case, though this patch doesn't fix any (known) problems, it
> still seems wise as a general policy to clear interrupt before handling
> them.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> Changes in v2: None
>
> drivers/usb/dwc2/core_intr.c | 55 ++++++++++++++++++++++----------------------
> drivers/usb/dwc2/hcd_intr.c | 16 ++++++-------
> 2 files changed, 35 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
> index 61601d16e233..2a166b7eec41 100644
> --- a/drivers/usb/dwc2/core_intr.c
> +++ b/drivers/usb/dwc2/core_intr.c
> @@ -80,15 +80,16 @@ static const char *dwc2_op_state_str(struct dwc2_hsotg *hsotg)
> */
> static void dwc2_handle_usb_port_intr(struct dwc2_hsotg *hsotg)
> {
> - u32 hprt0 = dwc2_readl(hsotg->regs + HPRT0);
> + u32 hprt0;
>
> + /* Clear interrupt */
> + dwc2_writel(GINTSTS_PRTINT, hsotg->regs + GINTSTS);
> +
> + hprt0 = dwc2_readl(hsotg->regs + HPRT0);
> if (hprt0 & HPRT0_ENACHG) {
> hprt0 &= ~HPRT0_ENA;
> dwc2_writel(hprt0, hsotg->regs + HPRT0);
> }
> -
> - /* Clear interrupt */
> - dwc2_writel(GINTSTS_PRTINT, hsotg->regs + GINTSTS);
> }
>
> /**
> @@ -98,11 +99,11 @@ static void dwc2_handle_usb_port_intr(struct dwc2_hsotg *hsotg)
> */
> static void dwc2_handle_mode_mismatch_intr(struct dwc2_hsotg *hsotg)
> {
> - dev_warn(hsotg->dev, "Mode Mismatch Interrupt: currently in %s mode\n",
> - dwc2_is_host_mode(hsotg) ? "Host" : "Device");
> -
> /* Clear interrupt */
> dwc2_writel(GINTSTS_MODEMIS, hsotg->regs + GINTSTS);
> +
> + dev_warn(hsotg->dev, "Mode Mismatch Interrupt: currently in %s mode\n",
> + dwc2_is_host_mode(hsotg) ? "Host" : "Device");
> }
>
> /**
> @@ -276,9 +277,13 @@ static void dwc2_handle_otg_intr(struct dwc2_hsotg *hsotg)
> */
> static void dwc2_handle_conn_id_status_change_intr(struct dwc2_hsotg *hsotg)
> {
> - u32 gintmsk = dwc2_readl(hsotg->regs + GINTMSK);
> + u32 gintmsk;
> +
> + /* Clear interrupt */
> + dwc2_writel(GINTSTS_CONIDSTSCHNG, hsotg->regs + GINTSTS);
>
> /* Need to disable SOF interrupt immediately */
> + gintmsk = dwc2_readl(hsotg->regs + GINTMSK);
> gintmsk &= ~GINTSTS_SOF;
> dwc2_writel(gintmsk, hsotg->regs + GINTMSK);
>
> @@ -295,9 +300,6 @@ static void dwc2_handle_conn_id_status_change_intr(struct dwc2_hsotg *hsotg)
> queue_work(hsotg->wq_otg, &hsotg->wf_otg);
> spin_lock(&hsotg->lock);
> }
> -
> - /* Clear interrupt */
> - dwc2_writel(GINTSTS_CONIDSTSCHNG, hsotg->regs + GINTSTS);
> }
>
> /**
> @@ -315,12 +317,12 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
> {
> int ret;
>
> - dev_dbg(hsotg->dev, "Session request interrupt - lx_state=%d\n",
> - hsotg->lx_state);
> -
> /* Clear interrupt */
> dwc2_writel(GINTSTS_SESSREQINT, hsotg->regs + GINTSTS);
>
> + dev_dbg(hsotg->dev, "Session request interrupt - lx_state=%d\n",
> + hsotg->lx_state);
> +
> if (dwc2_is_device_mode(hsotg)) {
> if (hsotg->lx_state == DWC2_L2) {
> ret = dwc2_exit_hibernation(hsotg, true);
> @@ -347,6 +349,10 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
> static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
> {
> int ret;
> +
> + /* Clear interrupt */
> + dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
> +
> dev_dbg(hsotg->dev, "++Resume or Remote Wakeup Detected Interrupt++\n");
> dev_dbg(hsotg->dev, "%s lxstate = %d\n", __func__, hsotg->lx_state);
>
> @@ -368,10 +374,9 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
> /* Change to L0 state */
> hsotg->lx_state = DWC2_L0;
> } else {
> - if (hsotg->core_params->hibernation) {
> - dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
> + if (hsotg->core_params->hibernation)
> return;
> - }
> +
> if (hsotg->lx_state != DWC2_L1) {
> u32 pcgcctl = dwc2_readl(hsotg->regs + PCGCTL);
>
> @@ -385,9 +390,6 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
> hsotg->lx_state = DWC2_L0;
> }
> }
> -
> - /* Clear interrupt */
> - dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
> }
>
> /*
> @@ -396,14 +398,14 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
> */
> static void dwc2_handle_disconnect_intr(struct dwc2_hsotg *hsotg)
> {
> + dwc2_writel(GINTSTS_DISCONNINT, hsotg->regs + GINTSTS);
> +
> dev_dbg(hsotg->dev, "++Disconnect Detected Interrupt++ (%s) %s\n",
> dwc2_is_host_mode(hsotg) ? "Host" : "Device",
> dwc2_op_state_str(hsotg));
>
> if (hsotg->op_state == OTG_STATE_A_HOST)
> dwc2_hcd_disconnect(hsotg, false);
> -
> - dwc2_writel(GINTSTS_DISCONNINT, hsotg->regs + GINTSTS);
> }
>
> /*
> @@ -419,6 +421,9 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg)
> u32 dsts;
> int ret;
>
> + /* Clear interrupt */
> + dwc2_writel(GINTSTS_USBSUSP, hsotg->regs + GINTSTS);
> +
> dev_dbg(hsotg->dev, "USB SUSPEND\n");
>
> if (dwc2_is_device_mode(hsotg)) {
> @@ -437,7 +442,7 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg)
> if (!dwc2_is_device_connected(hsotg)) {
> dev_dbg(hsotg->dev,
> "ignore suspend request before enumeration\n");
> - goto clear_int;
> + return;
> }
>
> ret = dwc2_enter_hibernation(hsotg);
> @@ -476,10 +481,6 @@ skip_power_saving:
> hsotg->op_state = OTG_STATE_A_HOST;
> }
> }
> -
> -clear_int:
> - /* Clear interrupt */
> - dwc2_writel(GINTSTS_USBSUSP, hsotg->regs + GINTSTS);
> }
>
> #define GINTMSK_COMMON (GINTSTS_WKUPINT | GINTSTS_SESSREQINT | \
> diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c
> index 03504ac2fecc..4c7f709b8182 100644
> --- a/drivers/usb/dwc2/hcd_intr.c
> +++ b/drivers/usb/dwc2/hcd_intr.c
> @@ -122,6 +122,9 @@ static void dwc2_sof_intr(struct dwc2_hsotg *hsotg)
> struct dwc2_qh *qh;
> enum dwc2_transaction_type tr_type;
>
> + /* Clear interrupt */
> + dwc2_writel(GINTSTS_SOF, hsotg->regs + GINTSTS);
> +
> #ifdef DEBUG_SOF
> dev_vdbg(hsotg->dev, "--Start of Frame Interrupt--\n");
> #endif
> @@ -146,9 +149,6 @@ static void dwc2_sof_intr(struct dwc2_hsotg *hsotg)
> tr_type = dwc2_hcd_select_transactions(hsotg);
> if (tr_type != DWC2_TRANSACTION_NONE)
> dwc2_hcd_queue_transactions(hsotg, tr_type);
> -
> - /* Clear interrupt */
> - dwc2_writel(GINTSTS_SOF, hsotg->regs + GINTSTS);
> }
>
> /*
> @@ -347,11 +347,12 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
> * Set flag and clear if detected
> */
> if (hprt0 & HPRT0_CONNDET) {
> + writel(hprt0_modify | HPRT0_CONNDET, hsotg->regs + HPRT0);
> +
> dev_vdbg(hsotg->dev,
> "--Port Interrupt HPRT0=0x%08x Port Connect Detected--\n",
> hprt0);
> dwc2_hcd_connect(hsotg);
> - hprt0_modify |= HPRT0_CONNDET;
>
> /*
> * The Hub driver asserts a reset when it sees port connect
> @@ -364,10 +365,10 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
> * Clear if detected - Set internal flag if disabled
> */
> if (hprt0 & HPRT0_ENACHG) {
> + writel(hprt0_modify | HPRT0_ENACHG, hsotg->regs + HPRT0);
> dev_vdbg(hsotg->dev,
> " --Port Interrupt HPRT0=0x%08x Port Enable Changed (now %d)--\n",
> hprt0, !!(hprt0 & HPRT0_ENA));
> - hprt0_modify |= HPRT0_ENACHG;
> if (hprt0 & HPRT0_ENA)
> dwc2_hprt0_enable(hsotg, hprt0, &hprt0_modify);
> else
> @@ -376,15 +377,12 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
>
> /* Overcurrent Change Interrupt */
> if (hprt0 & HPRT0_OVRCURRCHG) {
> + writel(hprt0_modify | HPRT0_OVRCURRCHG, hsotg->regs + HPRT0);
> dev_vdbg(hsotg->dev,
> " --Port Interrupt HPRT0=0x%08x Port Overcurrent Changed--\n",
> hprt0);
> hsotg->flags.b.port_over_current_change = 1;
> - hprt0_modify |= HPRT0_OVRCURRCHG;
> }
> -
> - /* Clear Port Interrupts */
> - dwc2_writel(hprt0_modify, hsotg->regs + HPRT0);
> }
>
> /*
>

Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: John Youn <johnyoun@synopsys.com>

Regards,
John