[U-Boot] [PATCH 4/5] fpga: virtex2: Add additional clock cycles after DONE assertion

[Michal Simek]

On 18. 06. 19 17:47, Robert Hancock wrote:
> Some Xilinx FPGA configuration options can result in the startup
> sequence extending past the end of the FPGA bitstream. Continue applying
> CCLK clock cycles for 8 cycles after DONE is asserted in order to ensure
> the startup sequence is complete, as recommended by Xilinx.
> 
> Signed-off-by: Robert Hancock <hancock at sedsystems.ca>
> ---
>  drivers/fpga/virtex2.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/fpga/virtex2.c b/drivers/fpga/virtex2.c
> index 2383c69..5028244 100644
> --- a/drivers/fpga/virtex2.c
> +++ b/drivers/fpga/virtex2.c
> @@ -247,6 +247,7 @@ static int virtex2_slave_post(xilinx_virtex2_slave_selectmap_fns *fn,
>  			      int cookie)
>  {
>  	int ret_val = FPGA_SUCCESS;
> +	int num_done = 0;
>  	unsigned long ts;
>  
>  	/*
> @@ -264,12 +265,18 @@ static int virtex2_slave_post(xilinx_virtex2_slave_selectmap_fns *fn,
>  
>  	/*
>  	 * Check for successful configuration.  FPGA INIT_B and DONE
> -	 * should both be high upon successful configuration.
> +	 * should both be high upon successful configuration. Continue pulsing
> +	 * clock with data set to all ones until DONE is asserted and for 8
> +	 * clock cycles afterwards.
>  	 */
>  	ts = get_timer(0);
> -	ret_val = FPGA_SUCCESS;
> -	while (((*fn->done)(cookie) == FPGA_FAIL) ||
> -	       (*fn->init)(cookie)) {
> +	while (true) {
> +		if ((*fn->done)(cookie) == FPGA_SUCCESS &&
> +		    !((*fn->init)(cookie))) {
> +			if (num_done++ >= 8)
> +				break;
> +		}
> +
>  		if (get_timer(ts) > CONFIG_SYS_FPGA_WAIT_CONFIG) {
>  			printf("%s:%d: ** Timeout after %d ticks waiting for DONE to assert and INIT to deassert\n",
>  			       __func__, __LINE__, CONFIG_SYS_FPGA_WAIT_CONFIG);
> @@ -277,6 +284,11 @@ static int virtex2_slave_post(xilinx_virtex2_slave_selectmap_fns *fn,
>  			ret_val = FPGA_FAIL;
>  			break;
>  		}
> +		(*fn->wdata) (0xff, true, cookie);
> +		CONFIG_FPGA_DELAY();
> +		(*fn->clk) (false, true, cookie);
> +		CONFIG_FPGA_DELAY();
> +		(*fn->clk) (true, true, cookie);


There are some functions which check if function is present before it is
called. I think that the whole driver should be sync in this to make
sure that functions are really implemented if code expects them or fail.

But this can be done on the top of this series.

Thanks,
Michal