linux-kernel - [RFC/PATCH 3/4] firmware_class: Provide infrastructure to make fw caching optional

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Message-Id: <1457428939-26659-4-git-send-email-stephen.boyd@linaro.org>
Date:	Tue,  8 Mar 2016 16:22:18 +0700
From:	Stephen Boyd <stephen.boyd@...aro.org>
To:	linux-kernel@...r.kernel.org
Cc:	Vikram Mulukutla <markivx@...eaurora.org>,
	linux-arm@...ts.infradead.org, Robin Murphy <robin.murphy@....com>,
	Laura Abbott <labbott@...hat.com>,
	Arnd Bergmann <arnd@...db.de>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mark Brown <broonie@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [RFC/PATCH 3/4] firmware_class: Provide infrastructure to make fw caching optional

From: Vikram Mulukutla <markivx@...eaurora.org>

Some low memory systems with complex peripherals cannot afford to
have the relatively large firmware images taking up valuable
memory during suspend and resume. Change the internal
implementation of firmware_class to disallow caching based on a
configurable option. In the near future, variants of
request_firmware will take advantage of this feature.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Vikram Mulukutla <markivx@...eaurora.org>
[stephen.boyd@...aro.org: Drop firmware_desc design and use flags]
Signed-off-by: Stephen Boyd <stephen.boyd@...aro.org>
---
 drivers/base/firmware_class.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index b9250e564ebf..9a616cf7ac9f 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -111,6 +111,7 @@ static inline long firmware_loading_timeout(void)
 #define FW_OPT_FALLBACK		0
 #endif
 #define FW_OPT_NO_WARN	(1U << 3)
+#define FW_OPT_NOCACHE	(1U << 4)
 
 struct firmware_cache {
 	/* firmware_buf instance will be added into the below list */
@@ -1095,14 +1096,16 @@ static int assign_firmware_buf(struct firmware *fw, struct device *device,
 	 * should be fixed in devres or driver core.
 	 */
 	/* don't cache firmware handled without uevent */
-	if (device && (opt_flags & FW_OPT_UEVENT))
+	if (device && (opt_flags & FW_OPT_UEVENT) &&
+	    !(opt_flags & FW_OPT_NOCACHE))
 		fw_add_devm_name(device, buf->fw_id);
 
 	/*
 	 * After caching firmware image is started, let it piggyback
 	 * on request firmware.
 	 */
-	if (buf->fwc->state == FW_LOADER_START_CACHE) {
+	if (!(opt_flags & FW_OPT_NOCACHE) &&
+	    buf->fwc->state == FW_LOADER_START_CACHE) {
 		if (fw_cache_piggyback_on_request(buf->fw_id))
 			kref_get(&buf->ref);
 	}
-- 
2.7.0.25.gfc10eb5