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Message-ID: <90e27f2b-4512-6121-c5f4-e7cb87b259ab@quicinc.com>
Date: Tue, 12 Sep 2023 16:39:07 -0700
From: Wesley Cheng <quic_wcheng@...cinc.com>
To: Stanley Chang <stanley_chang@...ltek.com>,
Thinh Nguyen <Thinh.Nguyen@...opsys.com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Felipe Balbi <balbi@...nel.org>, <linux-usb@...r.kernel.org>,
<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] usb: dwc3: core: configure TX/RX threshold for
DWC3_IP
Hi,
On 9/11/2023 9:19 PM, Stanley Chang wrote:
> In Synopsys's dwc3 data book:
> To avoid underrun and overrun during the burst, in a high-latency bus
> system (like USB), threshold and burst size control is provided through
> GTXTHRCFG and GRXTHRCFG registers.
>
> In Realtek DHC SoC, DWC3 USB 3.0 uses AHB system bus. When dwc3 is
> connected with USB 2.5G Ethernet, there will be overrun problem.
> Therefore, setting TX/RX thresholds can avoid this issue.
>
> Signed-off-by: Stanley Chang <stanley_chang@...ltek.com>
> ---
> v2 to v3 change:
> Move the threshold setting to new function dwc3_config_threshold.
> Add the threshold setting for usb31 and usb32
> v1 to v2 change:
> Add the properties for TX/RX threshold setting
> ---
> drivers/usb/dwc3/core.c | 160 +++++++++++++++++++++++++++++++---------
> drivers/usb/dwc3/core.h | 13 ++++
> 2 files changed, 137 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 9c6bf054f15d..44ee8526dc28 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1057,6 +1057,111 @@ static void dwc3_set_power_down_clk_scale(struct dwc3 *dwc)
> }
> }
>
> +static void dwc3_config_threshold(struct dwc3 *dwc)
> +{
> + u32 reg;
> + u8 rx_thr_num;
> + u8 rx_maxburst;
> + u8 tx_thr_num;
> + u8 tx_maxburst;
> +
> + /*
> + * Must config both number of packets and max burst settings to enable
> + * RX and/or TX threshold.
> + */
> + if (!DWC3_IP_IS(DWC3) && dwc->dr_mode == USB_DR_MODE_HOST) {
> + rx_thr_num = dwc->rx_thr_num_pkt_prd;
> + rx_maxburst = dwc->rx_max_burst_prd;
> + tx_thr_num = dwc->tx_thr_num_pkt_prd;
> + tx_maxburst = dwc->tx_max_burst_prd;
> +
> + if (rx_thr_num && rx_maxburst) {
> + reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
> + reg |= DWC31_RXTHRNUMPKTSEL_PRD;
> +
> + reg &= ~DWC31_RXTHRNUMPKT_PRD(~0);
> + reg |= DWC31_RXTHRNUMPKT_PRD(rx_thr_num);
> +
> + reg &= ~DWC31_MAXRXBURSTSIZE_PRD(~0);
> + reg |= DWC31_MAXRXBURSTSIZE_PRD(rx_maxburst);
> +
> + dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
> + }
> +
> + if (tx_thr_num && tx_maxburst) {
> + reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
> + reg |= DWC31_TXTHRNUMPKTSEL_PRD;
> +
> + reg &= ~DWC31_TXTHRNUMPKT_PRD(~0);
> + reg |= DWC31_TXTHRNUMPKT_PRD(tx_thr_num);
> +
> + reg &= ~DWC31_MAXTXBURSTSIZE_PRD(~0);
> + reg |= DWC31_MAXTXBURSTSIZE_PRD(tx_maxburst);
> +
> + dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
> + }
> + }
> +
> + rx_thr_num = dwc->rx_thr_num_pkt;
> + rx_maxburst = dwc->rx_max_burst;
> + tx_thr_num = dwc->tx_thr_num_pkt;
> + tx_maxburst = dwc->tx_max_burst;
> +
> + if (DWC3_IP_IS(DWC3)) {
> + if (rx_thr_num && rx_maxburst) {
> + reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
> + reg |= DWC3_GRXTHRCFG_PKTCNTSEL;
> +
> + reg &= ~DWC3_GRXTHRCFG_RXPKTCNT(~0);
> + reg |= DWC3_GRXTHRCFG_RXPKTCNT(rx_thr_num);
> +
> + reg &= ~DWC3_GRXTHRCFG_MAXRXBURSTSIZE(~0);
> + reg |= DWC3_GRXTHRCFG_MAXRXBURSTSIZE(rx_maxburst);
> +
> + dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
> + }
> +
> + if (tx_thr_num && tx_maxburst) {
> + reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
> + reg |= DWC3_GTXTHRCFG_PKTCNTSEL;
> +
> + reg &= ~DWC3_GTXTHRCFG_TXPKTCNT(~0);
> + reg |= DWC3_GTXTHRCFG_TXPKTCNT(tx_thr_num);
> +
> + reg &= ~DWC3_GTXTHRCFG_MAXTXBURSTSIZE(~0);
> + reg |= DWC3_GTXTHRCFG_MAXTXBURSTSIZE(tx_maxburst);
> +
> + dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
> + }
> + } else {
> + if (rx_thr_num && rx_maxburst) {
> + reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
> + reg |= DWC31_GRXTHRCFG_PKTCNTSEL;
> +
> + reg &= ~DWC31_GRXTHRCFG_RXPKTCNT(~0);
> + reg |= DWC31_GRXTHRCFG_RXPKTCNT(rx_thr_num);
> +
> + reg &= ~DWC31_GRXTHRCFG_MAXRXBURSTSIZE(~0);
> + reg |= DWC31_GRXTHRCFG_MAXRXBURSTSIZE(rx_maxburst);
> +
> + dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
> + }
> +
> + if (tx_thr_num && tx_maxburst) {
> + reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
> + reg |= DWC31_GTXTHRCFG_PKTCNTSEL;
> +
> + reg &= ~DWC31_GTXTHRCFG_TXPKTCNT(~0);
> + reg |= DWC31_GTXTHRCFG_TXPKTCNT(tx_thr_num);
> +
> + reg &= ~DWC31_GTXTHRCFG_MAXTXBURSTSIZE(~0);
> + reg |= DWC31_GTXTHRCFG_MAXTXBURSTSIZE(tx_maxburst);
> +
> + dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
> + }
> + }
> +}
> +
> /**
> * dwc3_core_init - Low-level initialization of DWC3 Core
> * @dwc: Pointer to our controller context structure
> @@ -1209,42 +1314,7 @@ static int dwc3_core_init(struct dwc3 *dwc)
> dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
> }
>
> - /*
> - * Must config both number of packets and max burst settings to enable
> - * RX and/or TX threshold.
> - */
> - if (!DWC3_IP_IS(DWC3) && dwc->dr_mode == USB_DR_MODE_HOST) {
> - u8 rx_thr_num = dwc->rx_thr_num_pkt_prd;
> - u8 rx_maxburst = dwc->rx_max_burst_prd;
> - u8 tx_thr_num = dwc->tx_thr_num_pkt_prd;
> - u8 tx_maxburst = dwc->tx_max_burst_prd;
> -
> - if (rx_thr_num && rx_maxburst) {
> - reg = dwc3_readl(dwc->regs, DWC3_GRXTHRCFG);
> - reg |= DWC31_RXTHRNUMPKTSEL_PRD;
> -
> - reg &= ~DWC31_RXTHRNUMPKT_PRD(~0);
> - reg |= DWC31_RXTHRNUMPKT_PRD(rx_thr_num);
> -
> - reg &= ~DWC31_MAXRXBURSTSIZE_PRD(~0);
> - reg |= DWC31_MAXRXBURSTSIZE_PRD(rx_maxburst);
> -
> - dwc3_writel(dwc->regs, DWC3_GRXTHRCFG, reg);
> - }
> -
> - if (tx_thr_num && tx_maxburst) {
> - reg = dwc3_readl(dwc->regs, DWC3_GTXTHRCFG);
> - reg |= DWC31_TXTHRNUMPKTSEL_PRD;
> -
> - reg &= ~DWC31_TXTHRNUMPKT_PRD(~0);
> - reg |= DWC31_TXTHRNUMPKT_PRD(tx_thr_num);
> -
> - reg &= ~DWC31_MAXTXBURSTSIZE_PRD(~0);
> - reg |= DWC31_MAXTXBURSTSIZE_PRD(tx_maxburst);
> -
> - dwc3_writel(dwc->regs, DWC3_GTXTHRCFG, reg);
> - }
> - }
> + dwc3_config_threshold(dwc);
>
> return 0;
>
> @@ -1380,6 +1450,10 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> u8 lpm_nyet_threshold;
> u8 tx_de_emphasis;
> u8 hird_threshold;
> + u8 rx_thr_num_pkt = 0;
> + u8 rx_max_burst = 0;
> + u8 tx_thr_num_pkt = 0;
> + u8 tx_max_burst = 0;
> u8 rx_thr_num_pkt_prd = 0;
> u8 rx_max_burst_prd = 0;
> u8 tx_thr_num_pkt_prd = 0;
> @@ -1442,6 +1516,14 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> "snps,usb2-lpm-disable");
> dwc->usb2_gadget_lpm_disable = device_property_read_bool(dev,
> "snps,usb2-gadget-lpm-disable");
> + device_property_read_u8(dev, "snps,rx-thr-num-pkt",
> + &rx_thr_num_pkt);
> + device_property_read_u8(dev, "snps,rx-max-burst",
> + &rx_max_burst);
> + device_property_read_u8(dev, "snps,tx-thr-num-pkt",
> + &tx_thr_num_pkt);
> + device_property_read_u8(dev, "snps,tx-max-burst",
> + &tx_max_burst);
Aren't there value limitations for some of these (if not all) settings?
For example, in the DWC3 programming guide, the max burst fields say
(for DWC31):
"Note: This field can only be set to 2, 4, 8 or 16."
And for the packet threshold count:
"Valid values are from 1 to 16."
Thanks
Wesley Cheng
> device_property_read_u8(dev, "snps,rx-thr-num-pkt-prd",
> &rx_thr_num_pkt_prd);
> device_property_read_u8(dev, "snps,rx-max-burst-prd",
> @@ -1523,6 +1605,12 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>
> dwc->hird_threshold = hird_threshold;
>
> + dwc->rx_thr_num_pkt = rx_thr_num_pkt;
> + dwc->rx_max_burst = rx_max_burst;
> +
> + dwc->tx_thr_num_pkt = tx_thr_num_pkt;
> + dwc->tx_max_burst = tx_max_burst;
> +
> dwc->rx_thr_num_pkt_prd = rx_thr_num_pkt_prd;
> dwc->rx_max_burst_prd = rx_max_burst_prd;
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index a69ac67d89fe..6782ec8bfd64 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -211,6 +211,11 @@
> #define DWC3_GRXTHRCFG_RXPKTCNT(n) (((n) & 0xf) << 24)
> #define DWC3_GRXTHRCFG_PKTCNTSEL BIT(29)
>
> +/* Global TX Threshold Configuration Register */
> +#define DWC3_GTXTHRCFG_MAXTXBURSTSIZE(n) (((n) & 0xff) << 16)
> +#define DWC3_GTXTHRCFG_TXPKTCNT(n) (((n) & 0xf) << 24)
> +#define DWC3_GTXTHRCFG_PKTCNTSEL BIT(29)
> +
> /* Global RX Threshold Configuration Register for DWC_usb31 only */
> #define DWC31_GRXTHRCFG_MAXRXBURSTSIZE(n) (((n) & 0x1f) << 16)
> #define DWC31_GRXTHRCFG_RXPKTCNT(n) (((n) & 0x1f) << 21)
> @@ -1045,6 +1050,10 @@ struct dwc3_scratchpad_array {
> * @test_mode_nr: test feature selector
> * @lpm_nyet_threshold: LPM NYET response threshold
> * @hird_threshold: HIRD threshold
> + * @rx_thr_num_pkt: USB receive packet count
> + * @rx_max_burst: max USB receive burst size
> + * @tx_thr_num_pkt: USB transmit packet count
> + * @tx_max_burst: max USB transmit burst size
> * @rx_thr_num_pkt_prd: periodic ESS receive packet count
> * @rx_max_burst_prd: max periodic ESS receive burst size
> * @tx_thr_num_pkt_prd: periodic ESS transmit packet count
> @@ -1273,6 +1282,10 @@ struct dwc3 {
> u8 test_mode_nr;
> u8 lpm_nyet_threshold;
> u8 hird_threshold;
> + u8 rx_thr_num_pkt;
> + u8 rx_max_burst;
> + u8 tx_thr_num_pkt;
> + u8 tx_max_burst;
> u8 rx_thr_num_pkt_prd;
> u8 rx_max_burst_prd;
> u8 tx_thr_num_pkt_prd;
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