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.
> 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 <nava.kishore.manne@xxxxxxx>
> ---
> 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
>
