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usb: dwc3: add power down scale setting 

Some SoC(e.g NXP imx8MQ) may have a wrong default power down scale
setting so need init it to be the correct value, the power down
scale setting description in DWC3 databook:

Power Down Scale (PwrDnScale)
The USB3 suspend_clk input replaces pipe3_rx_pclk as a clock source to
a small part of the USB3 core that operates when the SS PHY is in its
lowest power (P3) state, and therefore does not provide a clock.
The Power Down Scale field specifies how many suspend_clk periods fit
into a 16 kHz clock period. When performing the division, round up the
remainder.
For example, when using an 8-bit/16-bit/32-bit PHY and 25-MHz Suspend
clock,
Power Down Scale = 25000 kHz/16 kHz = 13'd1563 (rounder up)

So use the suspend clock rate to calculate it.

Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Li Jun <jun.li@nxp.com>
Link: https://lore.kernel.org/r/1654568404-3461-1-git-send-email-jun.li@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Li Jun 2022-06-07 10:20:04 +08:00 committed by Greg Kroah-Hartman
parent 8659ab3d93
commit 3497b9a5c8
2 changed files with 35 additions and 0 deletions
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34
drivers/usb/dwc3/core.c
View File

@ -1029,6 +1029,37 @@ static void dwc3_set_incr_burst_type(struct dwc3 *dwc)
dwc3_writel(dwc->regs, DWC3_GSBUSCFG0, cfg);
}
static void dwc3_set_power_down_clk_scale(struct dwc3 *dwc)
{
u32 scale;
u32 reg;
if (!dwc->susp_clk)
return;
/*
* The power down scale field specifies how many suspend_clk
* periods fit into a 16KHz clock period. When performing
* the division, round up the remainder.
*
* The power down scale value is calculated using the fastest
* frequency of the suspend_clk. If it isn't fixed (but within
* the accuracy requirement), the driver may not know the max
* rate of the suspend_clk, so only update the power down scale
* if the default is less than the calculated value from
* clk_get_rate() or if the default is questionably high
* (3x or more) to be within the requirement.
*/
scale = DIV_ROUND_UP(clk_get_rate(dwc->susp_clk), 16000);
reg = dwc3_readl(dwc->regs, DWC3_GCTL);
if ((reg & DWC3_GCTL_PWRDNSCALE_MASK) < DWC3_GCTL_PWRDNSCALE(scale) ||
(reg & DWC3_GCTL_PWRDNSCALE_MASK) > DWC3_GCTL_PWRDNSCALE(scale*3)) {
reg &= ~(DWC3_GCTL_PWRDNSCALE_MASK);
reg |= DWC3_GCTL_PWRDNSCALE(scale);
dwc3_writel(dwc->regs, DWC3_GCTL, reg);
}
}
/**
* dwc3_core_init - Low-level initialization of DWC3 Core
* @dwc: Pointer to our controller context structure
@ -1105,6 +1136,9 @@ static int dwc3_core_init(struct dwc3 *dwc)
if (ret)
goto err1;
/* Set power down scale of suspend_clk */
dwc3_set_power_down_clk_scale(dwc);
/* Adjust Frame Length */
dwc3_frame_length_adjustment(dwc);

1
drivers/usb/dwc3/core.h
View File

@ -231,6 +231,7 @@
/* Global Configuration Register */
#define DWC3_GCTL_PWRDNSCALE(n) ((n) << 19)
#define DWC3_GCTL_PWRDNSCALE_MASK GENMASK(31, 19)
#define DWC3_GCTL_U2RSTECN BIT(16)
#define DWC3_GCTL_RAMCLKSEL(x) (((x) & DWC3_GCTL_CLK_MASK) << 6)
#define DWC3_GCTL_CLK_BUS (0)