Merge "fastboot: Increase maximum usbfs bulk size for writes to 256KiB" into main (c0e1b607) · Commits · e / os / android_system_core

fastboot/usb_linux.cpp

+38 −20

Original line number	Diff line number	Diff line
		@@ -83,7 +83,18 @@ using namespace std::chrono_literals;
		// be reliable.
		// 256KiB seems to work, but 1MiB bulk transfers lock up my z620 with a 3.13
		// kernel.
		#define MAX_USBFS_BULK_SIZE (16 * 1024)
		// 128KiB was experimentally found to be enough to saturate the bus at
		// SuperSpeed+, so we first try double that for writes. If the operation fails
		// due to a lack of contiguous regions (or an ancient kernel), try smaller sizes
		// until we find one that works (see LinuxUsbTransport::Write). Reads are less
		// performance critical so for now just use a known good size.
		#define MAX_USBFS_BULK_WRITE_SIZE (256 * 1024)
		#define MAX_USBFS_BULK_READ_SIZE (16 * 1024)

		// This size should pretty much always work (it's compatible with pre-3.3
		// kernels and it's what we used to use historically), so if it doesn't work
		// something has gone badly wrong.
		#define MIN_USBFS_BULK_WRITE_SIZE (16 * 1024)

		struct usb_handle
		{
		@@ -108,6 +119,7 @@ class LinuxUsbTransport : public UsbTransport {
		private:
		std::unique_ptr<usb_handle> handle_;
		const uint32_t ms_timeout_;
		size_t max_usbfs_bulk_write_size_ = MAX_USBFS_BULK_WRITE_SIZE;

		DISALLOW_COPY_AND_ASSIGN(LinuxUsbTransport);
		};
		@@ -415,7 +427,8 @@ ssize_t LinuxUsbTransport::Write(const void* _data, size_t len)
		}

		auto submit_urb = [&](size_t i) {
		int xfer = (len > MAX_USBFS_BULK_SIZE) ? MAX_USBFS_BULK_SIZE : len;
		while (true) {
		int xfer = (len > max_usbfs_bulk_write_size_) ? max_usbfs_bulk_write_size_ : len;

		urb[i].type = USBDEVFS_URB_TYPE_BULK;
		urb[i].endpoint = handle_->ep_out;
		@@ -425,6 +438,10 @@ ssize_t LinuxUsbTransport::Write(const void* _data, size_t len)

		int n = ioctl(handle_->desc, USBDEVFS_SUBMITURB, &urb[i]);
		if (n != 0) {
		if (errno == ENOMEM && max_usbfs_bulk_write_size_ > MIN_USBFS_BULK_WRITE_SIZE) {
		max_usbfs_bulk_write_size_ /= 2;
		continue;
		}
		DBG("ioctl(USBDEVFS_SUBMITURB) failed\n");
		return false;
		}
		@@ -435,6 +452,7 @@ ssize_t LinuxUsbTransport::Write(const void* _data, size_t len)
		data += xfer;

		return true;
		}
		};

		auto reap_urb = [&](size_t i) {
		@@ -500,7 +518,7 @@ ssize_t LinuxUsbTransport::Read(void* _data, size_t len)
		}

		while (len > 0) {
		int xfer = (len > MAX_USBFS_BULK_SIZE) ? MAX_USBFS_BULK_SIZE : len;
		int xfer = (len > MAX_USBFS_BULK_READ_SIZE) ? MAX_USBFS_BULK_READ_SIZE : len;

		bulk.ep = handle_->ep_in;
		bulk.len = xfer;