[PATCH v1] firmware: microchip: auto-update: fix poll_complete() to not report spurious timeout errors

* [PATCH v1] firmware: microchip: auto-update: fix poll_complete() to not report spurious timeout errors
@ 2024-10-16 16:35 Conor Dooley
  2024-10-16 16:36 ` Conor Dooley
  2024-10-17 16:41 ` Conor Dooley
  0 siblings, 2 replies; 3+ messages in thread
From: Conor Dooley @ 2024-10-16 16:35 UTC (permalink / raw)
  To: Conor Dooley
  Cc: conor, Jamie Gibbons, Daire McNamara, linux-riscv, linux-kernel

From: Conor Dooley <conor.dooley@microchip.com>

fw_upload's poll_complete() is really intended for use with
asynchronous write() implementations - or at least those where the
write() loop may terminate without the kernel yet being aware of whether
or not the firmware upload has succeeded. For auto-update, write() is
only ever called once and will only return when uploading has completed,
be that by passing or failing. The core fw_upload code only calls
poll_complete() after the final call to write() has returned.

However, the poll_complete() implementation in the auto-update driver
was written to expect poll_complete() to be called from another context,
and it waits for a completion signalled from write(). Since
poll_complete() is actually called from the same context, after the
write() loop has terminated, wait_for_completion() never sees the
completion get signalled and always times out, causing programming to
always report a failing.

Since write() is full synchronous, and its return value will indicate
whether or not programming passed or failed, poll_complete() serves no
purpose and can be cut down to simply return FW_UPLOAD_ERR_NONE.

Fixes: ec5b0f1193ad4 ("firmware: microchip: add PolarFire SoC Auto Update support")
Reported-by: Jamie Gibbons <jamie.gibbons@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
CC: Conor Dooley <conor.dooley@microchip.com>
CC: Daire McNamara <daire.mcnamara@microchip.com>
CC: linux-riscv@lists.infradead.org
CC: linux-kernel@vger.kernel.org
---
 drivers/firmware/microchip/mpfs-auto-update.c | 42 ++++---------------
 1 file changed, 7 insertions(+), 35 deletions(-)

diff --git a/drivers/firmware/microchip/mpfs-auto-update.c b/drivers/firmware/microchip/mpfs-auto-update.c
index 9ca5ee58edbdf..0f7ec88482022 100644
--- a/drivers/firmware/microchip/mpfs-auto-update.c
+++ b/drivers/firmware/microchip/mpfs-auto-update.c
@@ -76,14 +76,11 @@
 #define AUTO_UPDATE_INFO_SIZE		SZ_1M
 #define AUTO_UPDATE_BITSTREAM_BASE	(AUTO_UPDATE_DIRECTORY_SIZE + AUTO_UPDATE_INFO_SIZE)
 
-#define AUTO_UPDATE_TIMEOUT_MS		60000
-
 struct mpfs_auto_update_priv {
 	struct mpfs_sys_controller *sys_controller;
 	struct device *dev;
 	struct mtd_info *flash;
 	struct fw_upload *fw_uploader;
-	struct completion programming_complete;
 	size_t size_per_bitstream;
 	bool cancel_request;
 };
@@ -156,19 +153,6 @@ static void mpfs_auto_update_cancel(struct fw_upload *fw_uploader)
 
 static enum fw_upload_err mpfs_auto_update_poll_complete(struct fw_upload *fw_uploader)
 {
-	struct mpfs_auto_update_priv *priv = fw_uploader->dd_handle;
-	int ret;
-
-	/*
-	 * There is no meaningful way to get the status of the programming while
-	 * it is in progress, so attempting anything other than waiting for it
-	 * to complete would be misplaced.
-	 */
-	ret = wait_for_completion_timeout(&priv->programming_complete,
-					  msecs_to_jiffies(AUTO_UPDATE_TIMEOUT_MS));
-	if (!ret)
-		return FW_UPLOAD_ERR_TIMEOUT;
-
 	return FW_UPLOAD_ERR_NONE;
 }
 
@@ -349,33 +333,23 @@ static enum fw_upload_err mpfs_auto_update_write(struct fw_upload *fw_uploader,
 						 u32 offset, u32 size, u32 *written)
 {
 	struct mpfs_auto_update_priv *priv = fw_uploader->dd_handle;
-	enum fw_upload_err err = FW_UPLOAD_ERR_NONE;
 	int ret;
 
-	reinit_completion(&priv->programming_complete);
-
 	ret = mpfs_auto_update_write_bitstream(fw_uploader, data, offset, size, written);
-	if (ret) {
-		err = FW_UPLOAD_ERR_RW_ERROR;
-		goto out;
-	}
+	if (ret)
+		return FW_UPLOAD_ERR_RW_ERROR;
 
-	if (priv->cancel_request) {
-		err = FW_UPLOAD_ERR_CANCELED;
-		goto out;
-	}
+	if (priv->cancel_request)
+		return FW_UPLOAD_ERR_CANCELED;
 
 	if (mpfs_auto_update_is_bitstream_info(data, size))
-		goto out;
+		return FW_UPLOAD_ERR_NONE;
 
 	ret = mpfs_auto_update_verify_image(fw_uploader);
 	if (ret)
-		err = FW_UPLOAD_ERR_FW_INVALID;
+		return FW_UPLOAD_ERR_FW_INVALID;
 
-out:
-	complete(&priv->programming_complete);
-
-	return err;
+	return FW_UPLOAD_ERR_NONE;
 }
 
 static const struct fw_upload_ops mpfs_auto_update_ops = {
@@ -461,8 +435,6 @@ static int mpfs_auto_update_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, ret,
 				     "The current bitstream does not support auto-update\n");
 
-	init_completion(&priv->programming_complete);
-
 	fw_uploader = firmware_upload_register(THIS_MODULE, dev, "mpfs-auto-update",
 					       &mpfs_auto_update_ops, priv);
 	if (IS_ERR(fw_uploader))
-- 
2.45.2


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