linux-kernel - [PATCH 03/15] fpga: dfl: fme: align PR buffer size per PR datawidth

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Message-Id: <20190628004951.6202-4-mdf@kernel.org>
Date:   Thu, 27 Jun 2019 17:49:39 -0700
From:   Moritz Fischer <mdf@...nel.org>
To:     linux-fpga@...r.kernel.org, gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        Wu Hao <hao.wu@...el.com>, Xu Yilun <yilun.xu@...el.com>,
        Alan Tull <atull@...nel.org>, Moritz Fischer <mdf@...nel.org>
Subject: [PATCH 03/15] fpga: dfl: fme: align PR buffer size per PR datawidth

From: Wu Hao <hao.wu@...el.com>

Current driver checks if input bitstream file size is aligned or
not per PR data width (default 32bits). It requires one additional
step for end user when they generate the bitstream file, padding
extra zeros to bitstream file to align its size per PR data width,
but they don't have to as hardware will drop extra padding bytes
automatically.

In order to simplify the user steps, this patch aligns PR buffer
size per PR data width in driver, to allow user to pass unaligned
size bitstream files to driver.

Signed-off-by: Xu Yilun <yilun.xu@...el.com>
Signed-off-by: Wu Hao <hao.wu@...el.com>
Acked-by: Alan Tull <atull@...nel.org>
Acked-by: Moritz Fischer <mdf@...nel.org>
Signed-off-by: Moritz Fischer <mdf@...nel.org>
---
 drivers/fpga/dfl-fme-pr.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/fpga/dfl-fme-pr.c b/drivers/fpga/dfl-fme-pr.c
index 6ec0f09e5994..3c71dc3faaf5 100644
--- a/drivers/fpga/dfl-fme-pr.c
+++ b/drivers/fpga/dfl-fme-pr.c
@@ -74,6 +74,7 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
 	struct dfl_fme *fme;
 	unsigned long minsz;
 	void *buf = NULL;
+	size_t length;
 	int ret = 0;
 	u64 v;
 
@@ -85,9 +86,6 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
 	if (port_pr.argsz < minsz || port_pr.flags)
 		return -EINVAL;
 
-	if (!IS_ALIGNED(port_pr.buffer_size, 4))
-		return -EINVAL;
-
 	/* get fme header region */
 	fme_hdr = dfl_get_feature_ioaddr_by_id(&pdev->dev,
 					       FME_FEATURE_ID_HEADER);
@@ -103,7 +101,13 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
 		       port_pr.buffer_size))
 		return -EFAULT;
 
-	buf = vmalloc(port_pr.buffer_size);
+	/*
+	 * align PR buffer per PR bandwidth, as HW ignores the extra padding
+	 * data automatically.
+	 */
+	length = ALIGN(port_pr.buffer_size, 4);
+
+	buf = vmalloc(length);
 	if (!buf)
 		return -ENOMEM;
 
@@ -140,7 +144,7 @@ static int fme_pr(struct platform_device *pdev, unsigned long arg)
 	fpga_image_info_free(region->info);
 
 	info->buf = buf;
-	info->count = port_pr.buffer_size;
+	info->count = length;
 	info->region_id = port_pr.port_id;
 	region->info = info;
 
-- 
2.22.0