Re: [PATCH] fpga: zynqmp: Make word align the configuration data
From: Xu Yilun <yilun.xu@intel.com>
Date: 2023-03-18 09:36:52
Also in:
linux-fpga, lkml
On 2023-03-14 at 15:12:22 +0530, Nava kishore Manne wrote:
To avoid unwanted copies at firmware(PMUFW) this patch provides a fix
The copy happens in firmware? Please help briefly describe the firmware operations in commit message.
quoted hunk
to align programmable logic(PL) configuration data if the data is not word-aligned. To align the configuration data this patch adds a few padding bytes and these additional padding bytes will not create any functional impact on the PL configuration. Signed-off-by: Nava kishore Manne <redacted> --- drivers/fpga/zynqmp-fpga.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)diff --git a/drivers/fpga/zynqmp-fpga.c b/drivers/fpga/zynqmp-fpga.c index c60f20949c47..70a12dc6e15c 100644 --- a/drivers/fpga/zynqmp-fpga.c +++ b/drivers/fpga/zynqmp-fpga.c@@ -15,6 +15,9 @@ /* Constant Definitions */ #define IXR_FPGA_DONE_MASK BIT(3) +#define DUMMY_PAD_BYTE 0xFF +#define FPGA_WORD_SIZE 4 + /** * struct zynqmp_fpga_priv - Private data structure * @dev: Device data structure@@ -41,18 +44,26 @@ static int zynqmp_fpga_ops_write(struct fpga_manager *mgr, const char *buf, size_t size) { struct zynqmp_fpga_priv *priv; + int word_align, ret, index; dma_addr_t dma_addr; u32 eemi_flags = 0; char *kbuf; - int ret; priv = mgr->priv; + word_align = size % FPGA_WORD_SIZE; + if (word_align) + word_align = FPGA_WORD_SIZE - word_align; + + size = size + word_align;
Does the Macro ALIGN() help?
kbuf = dma_alloc_coherent(priv->dev, size, &dma_addr, GFP_KERNEL); if (!kbuf) return -ENOMEM; - memcpy(kbuf, buf, size);
This is historical, but why do the realloc & copy? Any better way?
+ for (index = 0; index < word_align; index++) + kbuf[index] = DUMMY_PAD_BYTE; + + memcpy(&kbuf[index], buf, size - index);
Generally I object to massive copy in fpga_manager_ops::write if not necessary. If there is an alignment requirement from HW, it should be noticed to the caller in some way, before the buffer is created. Thanks, Yilun
wmb(); /* ensure all writes are done before initiate FW call */ -- 2.25.1
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