linux-kernel - [RFC/PATCHv3 v3 2/3] firmware: Provide infrastructure to make fw caching optional

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Date:	Tue, 10 May 2016 15:26:02 -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,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mark Brown <broonie@...nel.org>,
	Ming Lei <ming.lei@...onical.com>
Subject: [RFC/PATCHv3 v3 2/3] firmware: 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.

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 01d55723d82c..45ed20cefa10 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -112,6 +112,7 @@ 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 */
@@ -1065,14 +1066,16 @@ 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);
 	}
-- 
2.8.0.rc4