usb: dwc3: gadget: initialize NUMP based on RxFIFO Size
Instead of using burst size to configure NUMP, we
should be using RxFIFO Size instead. DWC3 is smart
enough to know that it shouldn't burst in case burst
size is 0.
Reported-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index bff2c35..eb28326 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -485,17 +485,6 @@
/* Burst size is only needed in SuperSpeed mode */
if (dwc->gadget.speed >= USB_SPEED_SUPER) {
u32 burst = dep->endpoint.maxburst;
- u32 nump;
- u32 reg;
-
- /* update NumP */
- reg = dwc3_readl(dwc->regs, DWC3_DCFG);
- nump = DWC3_DCFG_NUMP(reg);
- nump = max(nump, burst);
- reg &= ~DWC3_DCFG_NUMP_MASK;
- reg |= nump << DWC3_DCFG_NUMP_SHIFT;
- dwc3_writel(dwc->regs, DWC3_DCFG, reg);
-
params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst - 1);
}
@@ -1610,6 +1599,47 @@
static irqreturn_t dwc3_interrupt(int irq, void *_dwc);
static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc);
+/**
+ * dwc3_gadget_setup_nump - Calculate and initialize NUMP field of DCFG
+ * dwc: pointer to our context structure
+ *
+ * The following looks like complex but it's actually very simple. In order to
+ * calculate the number of packets we can burst at once on OUT transfers, we're
+ * gonna use RxFIFO size.
+ *
+ * To calculate RxFIFO size we need two numbers:
+ * MDWIDTH = size, in bits, of the internal memory bus
+ * RAM2_DEPTH = depth, in MDWIDTH, of internal RAM2 (where RxFIFO sits)
+ *
+ * Given these two numbers, the formula is simple:
+ *
+ * RxFIFO Size = (RAM2_DEPTH * MDWIDTH / 8) - 24 - 16;
+ *
+ * 24 bytes is for 3x SETUP packets
+ * 16 bytes is a clock domain crossing tolerance
+ *
+ * Given RxFIFO Size, NUMP = RxFIFOSize / 1024;
+ */
+static void dwc3_gadget_setup_nump(struct dwc3 *dwc)
+{
+ u32 ram2_depth;
+ u32 mdwidth;
+ u32 nump;
+ u32 reg;
+
+ ram2_depth = DWC3_GHWPARAMS7_RAM2_DEPTH(dwc->hwparams.hwparams7);
+ mdwidth = DWC3_GHWPARAMS0_MDWIDTH(dwc->hwparams.hwparams0);
+
+ nump = ((ram2_depth * mdwidth / 8) - 24 - 16) / 1024;
+ nump = min_t(u32, nump, 16);
+
+ /* update NumP */
+ reg = dwc3_readl(dwc->regs, DWC3_DCFG);
+ reg &= ~DWC3_DCFG_NUMP_MASK;
+ reg |= nump << DWC3_DCFG_NUMP_SHIFT;
+ dwc3_writel(dwc->regs, DWC3_DCFG, reg);
+}
+
static int __dwc3_gadget_start(struct dwc3 *dwc)
{
struct dwc3_ep *dep;
@@ -1670,6 +1700,8 @@
reg &= ~DWC3_GRXTHRCFG_PKTCNTSEL;
dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
+ dwc3_gadget_setup_nump(dwc);
+
/* Start with SuperSpeed Default */
dwc3_gadget_ep0_desc.wMaxPacketSize = cpu_to_le16(512);