From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (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 C49F731C567 for ; Wed, 15 Apr 2026 05:08:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776229707; cv=none; b=XB1kfh0Sn4zbbTgKXbv7KHsYa8TVk7+Zu7dQFfLPBxdiNZ3OTLY2aaY7dTnNbLG3rl5U0DkXL6q2WAsA9nA/h9cFzFtIJuAUdXreIBTMtHeH+xa4Hy591ivOrfRqPf0tEbnERQA49rh5HjQLg4u0wqb2IaF+FgB1+rwyJNHwqi8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776229707; c=relaxed/simple; bh=xo1DgEm+v+4CitQlUArtOELjVVPqS7ieeA8SZvBdteo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=dTu2z0gmThJsREv/33BNoT1o+s6T6cPmqebOrSGgPnBoQLN4LwGwPM+Y5CHAUycaC7gsyMWKnErPBQlk4KzmvPPU6dhqxUbvWoLzE/FF5mMlZTx7y3b4X/KTyKycm3dGrDrP6j8LJLWwDQEVfNfe3szNY4868//UsdnIHZLkX60= 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=VzamlGx1; arc=none smtp.client-ip=209.85.210.179 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="VzamlGx1" Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-82f68b3aaf7so72423b3a.0 for ; Tue, 14 Apr 2026 22:08:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1776229705; x=1776834505; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=eD/sVoyPZ+3rAECULNElpo4ngJXCE777D1kzkyumRTc=; b=VzamlGx1FHnm4FQpEmzOCgrqcyUpYR4vOiyetk0os8/u3SKsDCd6h5vtdwrWYmt0MQ njnhBMTz/9ATuxeMsdMEW2WWcfHKrqfQNowBmh1a/ShDqERhVhwhdFTSqITExitIky1s KUtX5Htj7kFEIDI1/Ldw0jpYEFALKOOcBL20M2TnE2Vp98C/a+/wA/wjObPZc4UHrSi1 poROuwJOwnXSxm+TjwyVmuFmlblNPq4/F3W5hY2+6GDFyxokw9bR1v4EhIHP7hqr7QIE j+61sXxeygWXA9jjzujxn+yxBW13pb/NOKRAWL0M7jeZDqL8Fs19SuTo7++XrzVzRP5M WHgw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776229705; x=1776834505; h=content-transfer-encoding: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; bh=eD/sVoyPZ+3rAECULNElpo4ngJXCE777D1kzkyumRTc=; b=iewnCH/gduz60teLwfPG0RkwN8B8TGLDtcA531tPUfVzOC6mYt7X3CM6J4gUt48Ttq RMRtj26+OvSUazlPCZo+UGegFkwk8+NcWnLnAarPWrpZPQmktOMIIEeFHMRetbNlQ+FM Op3docakvVhYz0I+c89i/QeSRRxlePFp41soERuzOm6Sp5qxYGidFcA6kddjQgVR9FoD co1m+Ypb1r84MoFJDs18R1gJGp8FJO7eylUQuvzJTh7zRuh4Xa3BNOhyMu1nvytSkMI/ beZi8UCz/lKpQMGk2bWmHFhqQp0GitwMhtqVCDgpPNjqABaRvxCVGNuEIb6aHP0JiPqV AMkQ== X-Forwarded-Encrypted: i=1; AFNElJ/b+tS6RqSdfG/IsKXpVThU5AkWSFlYyueMRMMqJLUrJufnf82y2M5XTLB3Q3+ly+kJD2PmbCtBLGM=@vger.kernel.org X-Gm-Message-State: AOJu0YyBGw3WPWbM3H00jVvR4hnCE7KsSIe+DMYgtARLajvy+EFnK6oE JlnwaxHEMPB5HmZBYthDWYrwlXWFWuxAurNqbW5v2NLGmsWKrvwwroDn X-Gm-Gg: AeBDieu+2w5vHLHoP8PTyHnXplMpvnTLZmYJWcWePTMX/66uTmZbx+nQttzypzE+5Zb VDgTSu/P8aGK+CGZucB72ruxPQSATtkgTRuWqHi3zLTfu51/hgjwhWh1F3f90fepUq7mXLb4kxm KiEtdkyx+K4rOOMSHaNVHQSys/tYkrq04/iMoSmZGZ4dnsiiRtIzpLC+LTY1QAQQmEvI100T6y6 0dEpw5W9h6wsdI/f6z4h9nEGSod1kPdb/YPMtT5Znc/AUfalZwsRtxjJxSEsWb2eMy3zUU5Qrem 63oewjeypnBYzekMBdPTnX81L2ZvAuauwy29a1RaQlw7OCCh5sFDExzF7xRQb2rlWgEpQtzmNKN 7JGDM7r+OBEOjGcT5tn3b8cJRtb7uEDLc5pEvR6d76lCgDmqT/pHFwKmpPmHu+0+RGPnzR/5goE 0uaMY7Qml2IdYO7kgKNJd4qClE0y0t9tkt3x8kDC+5yaj37iqvyXYMJQ0xC/c= X-Received: by 2002:a05:6a00:1ca9:b0:82f:5a27:10c9 with SMTP id d2e1a72fcca58-82f5a271a59mr4065059b3a.51.1776229705114; Tue, 14 Apr 2026 22:08:25 -0700 (PDT) Received: from hu-ckantibh-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82f67469dc3sm763706b3a.58.2026.04.14.22.08.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 22:08:24 -0700 (PDT) From: Sanjay Chitroda X-Google-Original-From: Sanjay Chitroda To: jic23@kernel.org Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, sanjayembeddedse@gmail.com, tglx@kernel.org, christophe.jaillet@wanadoo.fr, mingo@kernel.org, nabijaczleweli@nabijaczleweli.xyz, kees@kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 7/7] iio: ssp_sensors: reuse embedded RX buffer for SPI transfers Date: Wed, 15 Apr 2026 10:37:49 +0530 Message-Id: <20260415050749.3858046-8-sanjayembedded@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260415050749.3858046-1-sanjayembedded@gmail.com> References: <20260415050749.3858046-1-sanjayembedded@gmail.com> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Sanjay Chitroda Avoid allocating a temporary DMA buffer in the interrupt context when handling hub-to-AP and AP-to-hub SPI write messages. Replace the dynamically allocated RX buffer with a fixed-size, preallocated buffer embedded in the driver structure and reused for all SPI receive operations. This removes memory allocation from the IRQ path, simplifies lifetime management. No functional change intended. Signed-off-by: Sanjay Chitroda --- Changes in v6: - Replace dynamically allocated RX buffer with embedded fixed-size buffer - Fix struct layout to satisfy DMA alignment constraints comment from David - Link to v5: https://lore.kernel.org/all/20260406080852.2727453-1-sanjayembedded@gmail.com/ Changes in v5: - Rebase change on top of latest v5 patch series. Changes in v4: - Use preallocated buffer and stash a buffer that gets reused each time instead of a fresh allocation. - Link to v3: https://lore.kernel.org/all/20260315125509.857195-3-sanjayembedded@gmail.com/ Changes in v3: - prepare series to have all respective cleanup API support for the ssp_sensors following input from Andy Shevchenko - Link to v2 https://lore.kernel.org/all/20260311174151.3441429-1-sanjayembedded@gmail.com/ Changes in v2: - split series to individual patch - address review comment from Andy Shevchenko - Link to v1 https://lore.kernel.org/all/20260310200513.2162018-3-sanjayembedded@gmail.com/ --- drivers/iio/common/ssp_sensors/ssp.h | 3 +++ drivers/iio/common/ssp_sensors/ssp_spi.c | 20 ++------------------ 2 files changed, 5 insertions(+), 18 deletions(-) diff --git a/drivers/iio/common/ssp_sensors/ssp.h b/drivers/iio/common/ssp_sensors/ssp.h index f649cdecc277..8295bb7062a3 100644 --- a/drivers/iio/common/ssp_sensors/ssp.h +++ b/drivers/iio/common/ssp_sensors/ssp.h @@ -174,6 +174,7 @@ struct ssp_sensorhub_info { * @pending_list: pending list for messages queued to be sent/read * @sensor_devs: registered IIO devices table * @enable_refcount: enable reference count for wdt (watchdog timer) + * @rx_buf: buffer to receive SPI data * @header_buffer: cache aligned buffer for packet header */ struct ssp_data { @@ -221,6 +222,8 @@ struct ssp_data { struct iio_dev *sensor_devs[SSP_SENSOR_MAX]; atomic_t enable_refcount; + u8 rx_buf[SSP_DATA_PACKET_SIZE]; + __le16 header_buffer[SSP_HEADER_BUFFER_SIZE / sizeof(__le16)] __aligned(IIO_DMA_MINALIGN); }; diff --git a/drivers/iio/common/ssp_sensors/ssp_spi.c b/drivers/iio/common/ssp_sensors/ssp_spi.c index 92418721ff82..bab84b25edff 100644 --- a/drivers/iio/common/ssp_sensors/ssp_spi.c +++ b/drivers/iio/common/ssp_sensors/ssp_spi.c @@ -336,7 +336,7 @@ static int ssp_parse_dataframe(struct ssp_data *data, char *dataframe, int len) /* threaded irq */ int ssp_irq_msg(struct ssp_data *data) { - char *buffer; + char *buffer = data->rx_buf; u8 msg_type; int ret; u16 length, msg_options; @@ -380,19 +380,12 @@ int ssp_irq_msg(struct ssp_data *data) * but the slave should not send such ones - it is to * check but let's handle this */ - buffer = kmalloc(length, GFP_KERNEL | GFP_DMA); - if (!buffer) { - ret = -ENOMEM; - goto _unlock; - } /* got dead packet so it is always an error */ ret = spi_read(data->spi, buffer, length); if (ret >= 0) ret = -EPROTO; - kfree(buffer); - dev_err(SSP_DEV, "No match error %x\n", msg_options); @@ -425,22 +418,13 @@ int ssp_irq_msg(struct ssp_data *data) mutex_unlock(&data->pending_lock); break; case SSP_HUB2AP_WRITE: - buffer = kzalloc(length, GFP_KERNEL | GFP_DMA); - if (!buffer) - return -ENOMEM; - ret = spi_read(data->spi, buffer, length); if (ret < 0) { dev_err(SSP_DEV, "spi read fail\n"); - kfree(buffer); break; } - ret = ssp_parse_dataframe(data, buffer, length); - - kfree(buffer); - break; - + return ssp_parse_dataframe(data, buffer, length); default: dev_err(SSP_DEV, "unknown msg type\n"); return -EPROTO; -- 2.34.1