From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f52.google.com (mail-pj1-f52.google.com [209.85.216.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A9C2646A612 for ; Thu, 30 Jul 2026 16:21:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.52 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785428520; cv=none; b=KpPuM6yjtxMmBpcdv6AAuqqiXID6bIMLPeDDcS0HVmfrfhgi2StCO7PF8gK42/hHd3PqSRvRzauvxRqZy02s0reUUsW5131eWImX6kCu8xmAxNLs89bYEoUQHzuJZIXCryqdsxgmYLUiYrH4NymcjV6m8XCq1f6qMphNKrc3ZsM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785428520; c=relaxed/simple; bh=UrR8l2e2ua0r8hL++ntP47TXScInY+OVnratMs3ND84=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=F5v4/y7L3fHdhU3FKHpYY9cBqIMY0rgYdB43rTIlXav9iZv7JJ/ma1fi//UKTehQqTLyHEdUTUljKYHDRIDL52Uuh3iTnZ8xEFAL1NAT60C3FJwUjs4r/wl3FoATEi6KQEenS/JUUPXAQ24xrWvV7kMN2tfQgoCrPsIduI+IZts= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=UA1S4A63; arc=none smtp.client-ip=209.85.216.52 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="UA1S4A63" Received: by mail-pj1-f52.google.com with SMTP id 98e67ed59e1d1-380f3c1b087so5445a91.3 for ; Thu, 30 Jul 2026 09:21:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785428518; x=1786033318; darn=lists.linux.dev; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to:content-type; bh=9KRSCmcUKJkgpKNhWDdTfQ1+nI5nYS2/gN/zLauhACk=; b=UA1S4A63yDthlhdLFlSzf4rQQ5uA4heQ/DkuGJ2WUlscTEDivaU8i29Hp8IUN1/aWf Ka6ob4HiTGqi+5kbqe/bNI8wmQ1xpayLg6iE+v5ESAfcn30p/9iISn2+sHLmgScq6AG8 Nx9tC00SZIJNTo60LwHpMwgk476UaDJGIeHVV72B7L29E8V34uUyOuMetFCCFTqPGylZ 2C/ZEZvnyUbfZA2PUW6PqDxNUZ09BJworwsD+qx8MhnEf8MF/+K9Xzzn6i5ZIvn6O3aQ iUqx8+LWbgvfuc3lxpYbLp5hfYzdpfBZGhzqXcn8+mcUczXhYQ3dl414wDnNckiH+5Vz 7K2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785428518; x=1786033318; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=9KRSCmcUKJkgpKNhWDdTfQ1+nI5nYS2/gN/zLauhACk=; b=oJpxIItut4+XHFnWNmkJTnPbrIPFk9/P5JK3n8FBm/od3PoacMmVXU6MdIQEq5xsSx Clev2+NDRMzIPDUqtmiUyk+aO4yzt7ubnhv+PIG7L5M3gFFAQ+t2E7+gDHNgtV9+Fz50 mgEBuoUvPhxkwbDT+tLio/zXVok0CQKKfgjEQpqNT6xB0tCBWlN14gA1wFDn1F7fOlFR bfpSRam9mUsYpzyHL1glYjI7x+TDYR1ud0Ww7k0K5YZNFVnNndarIIaOUnJ0zHBcsQ+P 1E6URcE3s7iqYbI/MNSg4bCw0X0hbapPxVfDImJzI8QdSWTWxJqf+R/qsu/qwcJ4G1P8 lbWA== X-Forwarded-Encrypted: i=1; AHgh+RpDT7v4uH8/gjdQQSMQcWUneKFddVnWBcYmr1yQnwRkoXK17dNGYNMu5o6RHZCo7QOMxJFAs9TphxM=@lists.linux.dev X-Gm-Message-State: AOJu0YytWqZhzsi1jZu/PcjnjicqKKDiU1t04hds7+tckkM9uLVEY1Uo afZQ3vdyI5nFa3ARH+OX6XKYfc6Iia4JHvCY4jJasE7VOQ5KJmJrlVf0dfpOQ/De9Qs= X-Gm-Gg: AR+sD10EFrmPp0uSC+PifRajK9ebr1UEHKUaeloXXiVkFW/CsMikkTiq6MLk8fK9ndX MvYmAmPFAUI5ss/p7wCa8uAnX29ave4Vd34eMdjzGEuwTTf9fhsS+cUouv4AaWtUPSfrNUtHiDP XUFUJfbgNi4fJ5C9Yt4Cn4xiy4m7rAQPTUGUEWqoHdaPhFFTqtkmUKPFtJ/n3cAfdzsesxfgUiG 68uDwe4+90yKf9nDEu9V1thROLtKXJ9af0Z5tSri5CWXhJGRwvV+Dz+Wu6iY2XRQASBeofYTiSC a/6WvT6bpXxhfO4VDwleuI6MgMmfrSG6j7T9qZuAZzQ8Xqd3eqQPn+Rp87Fddxx9uJskCR3NTPA of7d3dTQxd9OVITu13sFIM8OkrUUJ3D35gXk7Jvqs/OIrQVqQUujOYGrLnnIbHVLjJ+4NcZrEcS vWGyetBPE2KtIDQ5f2w+lLafBVfDoFiTrCNHCHN8yGiVNQ7UhtVC7Tclgtf2fgI6vdUAFxGFTiG Io= X-Received: by 2002:a17:90b:1dcc:b0:381:bcfb:e710 with SMTP id 98e67ed59e1d1-38fa8041704mr871174a91.3.1785428517991; Thu, 30 Jul 2026 09:21:57 -0700 (PDT) Received: from Potato.tail66a299.ts.net ([171.76.83.76]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13e7275973dsm19964269c88.15.2026.07.30.09.21.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2026 09:21:57 -0700 (PDT) From: Shivesh X-Google-Original-From: Shivesh To: arend.vanspriel@broadcom.com Cc: linux-wireless@vger.kernel.org, brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com, linux-kernel@vger.kernel.org, Shivesh Subject: [PATCH v2 6/8] wifi: brcmfmac: pcie: optimize latency and irq teardown Date: Thu, 30 Jul 2026 16:21:09 +0000 Message-ID: <20260730162135.12278-6-shivesh@example.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260730162135.12278-1-shivesh@example.com> References: <20260730162135.12278-1-shivesh@example.com> Precedence: bulk X-Mailing-List: brcm80211@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Shivesh Optimizes mailbox polling with exponential backoff rather than a fixed msleep(10) loop. Fixes define names. Eliminates coarse msleep(50) delays during IRQ teardown by replacing them with tight usleep_range polling. Signed-off-by: Shivesh --- .../broadcom/brcm80211/brcmfmac/pcie.c | 66 ++++++++++++++++--- 1 file changed, 58 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c index 13662aa4b4ea..9338a5faa260 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/pcie.c @@ -268,6 +268,27 @@ static const struct brcmf_firmware_mapping brcmf_pcie_fwnames[] = { #define BRCMF_PCIE_MBDATA_TIMEOUT msecs_to_jiffies(2000) +/* + * H2D mailbox poll timing parameters. + * + * The dongle typically clears the H2D mailbox register within a few + * hundred microseconds after the doorbell interrupt fires. The + * original code used msleep(10) * 100 iterations, meaning the + * minimum observable latency was 10ms even when the dongle was fast. + * + * We instead start with a short sleep and double it each iteration + * (exponential backoff) up to BRCMF_PCIE_MB_POLL_MAX_US, staying + * within the same 1-second absolute timeout. + * + * MIN_US / INITIAL_MAX_US : usleep_range bounds for the first iteration. + * MAX_US : cap on the per-iteration sleep (µs). + * TIMEOUT_US : total budget before giving up (1 second). + */ +#define BRCMF_PCIE_MB_POLL_MIN_US 40 +#define BRCMF_PCIE_MB_POLL_INITIAL_MAX_US 50 +#define BRCMF_PCIE_MB_POLL_MAX_US 5000 +#define BRCMF_PCIE_MB_POLL_TIMEOUT_US 1000000 + #define BRCMF_PCIE_CFGREG_STATUS_CMD 0x4 #define BRCMF_PCIE_CFGREG_PM_CSR 0x4C #define BRCMF_PCIE_CFGREG_MSI_CAP 0x58 @@ -766,7 +787,8 @@ brcmf_pcie_send_mb_data(struct brcmf_pciedev_info *devinfo, u32 htod_mb_data) struct brcmf_core *core; u32 addr; u32 cur_htod_mb_data; - u32 i; + u32 elapsed_us = 0; + u32 sleep_us = BRCMF_PCIE_MB_POLL_INITIAL_MAX_US; shared = &devinfo->shared; addr = shared->htod_mb_data_addr; @@ -776,12 +798,40 @@ brcmf_pcie_send_mb_data(struct brcmf_pciedev_info *devinfo, u32 htod_mb_data) brcmf_dbg(PCIE, "MB transaction is already pending 0x%04x\n", cur_htod_mb_data); - i = 0; + /* + * Wait for the dongle to consume the previous H2D mailbox message. + * + * There is no interrupt that signals when the dongle clears this + * register, so polling is unavoidable. The original code used + * msleep(10) per iteration, incurring at least 10ms of latency + * even when the dongle responded in microseconds. + * + * We use usleep_range() with exponential backoff instead: + * - First iteration sleeps ~50µs (fast path for responsive dongle). + * - Each subsequent iteration doubles the sleep, capped at 5ms, + * so long waits still yield the CPU without busy-spinning. + * - Total timeout matches the original 1-second limit. + * - We bail early if the device has gone down so that a dead + * dongle does not hold the caller for a full second. + */ while (cur_htod_mb_data != 0) { - msleep(10); - i++; - if (i > 100) + if (devinfo->state == BRCMFMAC_PCIE_STATE_DOWN) { + brcmf_dbg(PCIE, "Device down, aborting MB send\n"); return -EIO; + } + + if (elapsed_us >= BRCMF_PCIE_MB_POLL_TIMEOUT_US) { + brcmf_err("Timeout waiting for H2D MB slot after %u us\n", + elapsed_us); + return -EIO; + } + + usleep_range(BRCMF_PCIE_MB_POLL_MIN_US, sleep_us); + elapsed_us += sleep_us; + + /* Exponential backoff, capped at BRCMF_PCIE_MB_POLL_MAX_US */ + sleep_us = min(sleep_us * 2, (u32)BRCMF_PCIE_MB_POLL_MAX_US); + cur_htod_mb_data = brcmf_pcie_read_tcm32(devinfo, addr); } @@ -1001,10 +1051,10 @@ static void brcmf_pcie_release_irq(struct brcmf_pciedev_info *devinfo) free_irq(pdev->irq, devinfo); pci_disable_msi(pdev); - msleep(50); + usleep_range(1000, 2000); count = 0; - while ((devinfo->in_irq) && (count < 20)) { - msleep(50); + while ((devinfo->in_irq) && (count < 1000)) { + usleep_range(1000, 2000); count++; } if (devinfo->in_irq) -- 2.53.0