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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Serge Semin <Sergey.Semin@baikalelectronics.ru>,
	Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: [PATCH 4.19 28/50] usb: dwc3: ulpi: Replace CPU-based busyloop with Protocol-based one
Date: Mon, 22 Feb 2021 13:13:19 +0100
Message-ID: <20210222121025.288077989@linuxfoundation.org> (raw)
In-Reply-To: <20210222121019.925481519@linuxfoundation.org>

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

commit fca3f138105727c3a22edda32d02f91ce1bf11c9 upstream

Originally the procedure of the ULPI transaction finish detection has been
developed as a simple busy-loop with just decrementing counter and no
delays. It's wrong since on different systems the loop will take a
different time to complete. So if the system bus and CPU are fast enough
to overtake the ULPI bus and the companion PHY reaction, then we'll get to
take a false timeout error. Fix this by converting the busy-loop procedure
to take the standard bus speed, address value and the registers access
mode into account for the busy-loop delay calculation.

Here is the way the fix works. It's known that the ULPI bus is clocked
with 60MHz signal. In accordance with [1] the ULPI bus protocol is created
so to spend 5 and 6 clock periods for immediate register write and read
operations respectively, and 6 and 7 clock periods - for the extended
register writes and reads. Based on that we can easily pre-calculate the
time which will be needed for the controller to perform a requested IO
operation. Note we'll still preserve the attempts counter in case if the
DWC USB3 controller has got some internals delays.

[1] UTMI+ Low Pin Interface (ULPI) Specification, Revision 1.1,
    October 20, 2004, pp. 30 - 36.

Fixes: 88bc9d194ff6 ("usb: dwc3: add ULPI interface support")
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210085008.13264-3-Sergey.Semin@baikalelectronics.ru
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/dwc3/ulpi.c |   18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

--- a/drivers/usb/dwc3/ulpi.c
+++ b/drivers/usb/dwc3/ulpi.c
@@ -7,6 +7,8 @@
  * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
  */
 
+#include <linux/delay.h>
+#include <linux/time64.h>
 #include <linux/ulpi/regs.h>
 
 #include "core.h"
@@ -17,12 +19,22 @@
 		DWC3_GUSB2PHYACC_ADDR(ULPI_ACCESS_EXTENDED) | \
 		DWC3_GUSB2PHYACC_EXTEND_ADDR(a) : DWC3_GUSB2PHYACC_ADDR(a))
 
-static int dwc3_ulpi_busyloop(struct dwc3 *dwc)
+#define DWC3_ULPI_BASE_DELAY	DIV_ROUND_UP(NSEC_PER_SEC, 60000000L)
+
+static int dwc3_ulpi_busyloop(struct dwc3 *dwc, u8 addr, bool read)
 {
+	unsigned long ns = 5L * DWC3_ULPI_BASE_DELAY;
 	unsigned int count = 1000;
 	u32 reg;
 
+	if (addr >= ULPI_EXT_VENDOR_SPECIFIC)
+		ns += DWC3_ULPI_BASE_DELAY;
+
+	if (read)
+		ns += DWC3_ULPI_BASE_DELAY;
+
 	while (count--) {
+		ndelay(ns);
 		reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYACC(0));
 		if (reg & DWC3_GUSB2PHYACC_DONE)
 			return 0;
@@ -47,7 +59,7 @@ static int dwc3_ulpi_read(struct device
 	reg = DWC3_GUSB2PHYACC_NEWREGREQ | DWC3_ULPI_ADDR(addr);
 	dwc3_writel(dwc->regs, DWC3_GUSB2PHYACC(0), reg);
 
-	ret = dwc3_ulpi_busyloop(dwc);
+	ret = dwc3_ulpi_busyloop(dwc, addr, true);
 	if (ret)
 		return ret;
 
@@ -71,7 +83,7 @@ static int dwc3_ulpi_write(struct device
 	reg |= DWC3_GUSB2PHYACC_WRITE | val;
 	dwc3_writel(dwc->regs, DWC3_GUSB2PHYACC(0), reg);
 
-	return dwc3_ulpi_busyloop(dwc);
+	return dwc3_ulpi_busyloop(dwc, addr, false);
 }
 
 static const struct ulpi_ops dwc3_ulpi_ops = {



  parent reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-22 12:12 [PATCH 4.19 00/50] 4.19.177-rc1 review Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 01/50] tracing: Do not count ftrace events in top level enable output Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 02/50] tracing: Check length before giving out the filter buffer Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 03/50] arm/xen: Dont probe xenbus as part of an early initcall Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 04/50] arm64: dts: rockchip: Fix PCIe DT properties on rk3399 Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 05/50] platform/x86: hp-wmi: Disable tablet-mode reporting by default Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 06/50] ovl: perform vfs_getxattr() with mounter creds Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 07/50] cap: fix conversions on getxattr Greg Kroah-Hartman
2021-02-22 12:12 ` [PATCH 4.19 08/50] ovl: skip getxattr of security labels Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 09/50] drm/amd/display: Fix dc_sink kref count in emulated_link_detect Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 10/50] drm/amd/display: Free atomic state after drm_atomic_commit Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 11/50] riscv: virt_addr_valid must check the address belongs to linear mapping Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 12/50] bfq-iosched: Revert "bfq: Fix computation of shallow depth" Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 13/50] ARM: dts: lpc32xx: Revert set default clock rate of HCLK PLL Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 14/50] ARM: ensure the signal page contains defined contents Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 15/50] ARM: kexec: fix oops after TLB are invalidated Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 16/50] mt76: dma: fix a possible memory leak in mt76_add_fragment() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 17/50] bpf: Check for integer overflow when using roundup_pow_of_two() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 18/50] netfilter: xt_recent: Fix attempt to update deleted entry Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 19/50] netfilter: flowtable: fix tcp and udp header checksum update Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 20/50] xen/netback: avoid race in xenvif_rx_ring_slots_available() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 21/50] net: stmmac: set TxQ mode back to DCB after disabling CBS Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 22/50] netfilter: conntrack: skip identical origin tuple in same zone only Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 23/50] net: hns3: add a check for queue_id in hclge_reset_vf_queue() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 24/50] firmware_loader: align .builtin_fw to 8 Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 25/50] i2c: stm32f7: fix configuration of the digital filter Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 26/50] h8300: fix PREEMPTION build, TI_PRE_COUNT undefined Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 27/50] usb: dwc3: ulpi: fix checkpatch warning Greg Kroah-Hartman
2021-02-22 12:13 ` Greg Kroah-Hartman [this message]
2021-02-22 12:13 ` [PATCH 4.19 29/50] net: fix iteration for sctp transport seq_files Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 30/50] net/vmw_vsock: improve locking in vsock_connect_timeout() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 31/50] net: watchdog: hold device global xmit lock during tx disable Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 32/50] vsock/virtio: update credit only if socket is not closed Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 33/50] vsock: fix locking in vsock_shutdown() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 34/50] net/rds: restrict iovecs length for RDS_CMSG_RDMA_ARGS Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 35/50] net/qrtr: restrict user-controlled length in qrtr_tun_write_iter() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 36/50] ovl: expand warning in ovl_d_real() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 37/50] x86/build: Disable CET instrumentation in the kernel for 32-bit too Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 38/50] KVM: SEV: fix double locking due to incorrect backport Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 39/50] net: qrtr: Fix port ID for control messages Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 40/50] Xen/x86: dont bail early from clear_foreign_p2m_mapping() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 41/50] Xen/x86: also check kernel mapping in set_foreign_p2m_mapping() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 42/50] Xen/gntdev: correct dev_bus_addr handling in gntdev_map_grant_pages() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 43/50] Xen/gntdev: correct error checking " Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 44/50] xen/arm: dont ignore return errors from set_phys_to_machine Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 45/50] xen-blkback: dont "handle" error by BUG() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 46/50] xen-netback: " Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 47/50] xen-scsiback: " Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 48/50] xen-blkback: fix error handling in xen_blkbk_map() Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 49/50] scsi: qla2xxx: Fix crash during driver load on big endian machines Greg Kroah-Hartman
2021-02-22 12:13 ` [PATCH 4.19 50/50] kvm: check tlbs_dirty directly Greg Kroah-Hartman
2021-02-22 18:40 ` [PATCH 4.19 00/50] 4.19.177-rc1 review Pavel Machek
2021-02-22 21:28 ` Guenter Roeck
2021-02-22 21:49 ` Igor
2021-02-23 10:10 ` Naresh Kamboju
2021-02-23 21:17 ` Shuah Khan

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