[U-Boot] [PATCH 1/2] arm: socfpga: mmc: Enable calibration for drvsel and smpsel

[Marek Vasut]

On Wednesday, August 19, 2015 at 07:54:50 AM, Chin Liang See wrote:
> Enable SDMMC calibration to determine the best setting for
> drvsel and smpsel. It will be triggered whenever there is
> a change of card frequency and bus width. This is to ensure
> reliable transmission between the controller and the card.
> 
> Signed-off-by: Chin Liang See <clsee at altera.com>
> Cc: Dinh Nguyen <dinguyen at opensource.altera.com>
> Cc: Pavel Machek <pavel at denx.de>
> Cc: Marek Vasut <marex at denx.de>
> Cc: Wolfgang Denk <wd at denx.de>
> Cc: Stefan Roese <sr at denx.de>
> Cc: Tom Rini <trini at konsulko.com>
> ---
>  drivers/mmc/socfpga_dw_mmc.c |  187
> ++++++++++++++++++++++++++++++++++++++++-- 1 files changed, 180
> insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/socfpga_dw_mmc.c b/drivers/mmc/socfpga_dw_mmc.c
> index eb69aed..15e537c 100644
> --- a/drivers/mmc/socfpga_dw_mmc.c
> +++ b/drivers/mmc/socfpga_dw_mmc.c
> @@ -11,25 +11,140 @@
>  #include <asm/arch/dwmmc.h>
>  #include <asm/arch/clock_manager.h>
>  #include <asm/arch/system_manager.h>
> +#include "mmc_private.h"
> 
>  static const struct socfpga_clock_manager *clock_manager_base =
>  		(void *)SOCFPGA_CLKMGR_ADDRESS;
>  static const struct socfpga_system_manager *system_manager_base =
>  		(void *)SOCFPGA_SYSMGR_ADDRESS;
> 
> -static void socfpga_dwmci_clksel(struct dwmci_host *host)
> +#define CAL_ROWS     7
> +#define CAL_COLS     8
> +
> +/*
> + * This function determines the largest rectangle filled with 1's and
> returns + * the middle. This functon can be optimized, for example using
> the algorithm + * from
> http://www.drdobbs.com/database/the-maximal-rectangle-problem/184410529 +
> * It currently takes less than 1ms, while creating the input data takes
> ~5ms + * so there is not a real need to optimize it.
> + */
> +int find_calibration_point(unsigned char cal_results[CAL_ROWS][CAL_COLS],
> +unsigned int sum, unsigned int * cal_row, unsigned int * cal_col)
>  {
> -	unsigned int drvsel;
> -	unsigned int smplsel;
> +	/* Structure containing a rectangle candidate */
> +	typedef struct
> +	{
> +		unsigned char height;
> +		unsigned char width;
> +		unsigned short area;
> +	} rect_cand_t;
> +
> +	/* Array with the rectangle candidates */
> +	rect_cand_t rect_cands[CAL_ROWS * CAL_COLS];
> +	unsigned char cr_rect_cand = 0;
> +	unsigned char height, width, k;
> +
> +	/* No solution if all combinations fail */
> +	if(sum == 0)
> +		return 1;
> +
> +	/* Simple solution if all combinations pass */
> +	if(sum == (CAL_ROWS * CAL_COLS)) {
> +		*cal_row = (CAL_ROWS - 1) / 2;
> +		*cal_col = (CAL_COLS - 1) / 2;
> +		return 0;
> +	}
> +
> +	/*
> +	 * Create list of all possible sub-rectangles, in descending area
> +	 * order
> +	 */
> +	for(height = CAL_ROWS; height >= 1; height--) {
> +		for(width = CAL_COLS; width >= 1 ; width--){
> +			/* Add a new rectangle candidate */
> +			rect_cands[cr_rect_cand].height = height;
> +			rect_cands[cr_rect_cand].width = width;
> +			rect_cands[cr_rect_cand].area = height * width;
> +			cr_rect_cand++;
> +
> +			/* First candidate it always in the right position */
> +			if(cr_rect_cand == 1)
> +				continue;
> +
> +			/*
> +			 * Put the candidate in right location to maintain
> +			 * descending order
> +			 */
> +			for(k = cr_rect_cand - 1; k > 1; k--){
> +				if(rect_cands[k-1].area < rect_cands[k].area){
> +					rect_cand_t tmp = rect_cands[k-1];
> +					rect_cands[k-1] = rect_cands[k];
> +					rect_cands[k] = tmp;
> +				} else
> +					break;
> +			}
> +		}
> +	}
> +
> +	/* Try to fit the rectangle candidates, in descending area order */
> +	for(k = 0; k < CAL_ROWS * CAL_COLS; k++) {
> +		unsigned char start_row, start_col;
> +		unsigned rect_width = rect_cands[k].width;
> +		unsigned rect_height = rect_cands[k].height;
> +
> +		/* Find the row and column where the candidate fits */
> +		for (start_col = 0; start_col < (CAL_COLS - rect_width + 1);
> +		     start_col++) {
> +			for (start_row = 0; start_row < (CAL_ROWS -
> +			     rect_height + 1); start_row++) {
> +				unsigned ok = 1;
> +				unsigned add_col, add_row;
> +
> +				/* Determine if the rectangle fits here */
> +				for (add_col = 0; (add_col < rect_width) && ok;
> +				     add_col++) {
> +					for (add_row = 0; add_row < rect_height;
> +					     add_row++) {
> +						if (!cal_results
> +						   [start_row+add_row][start_col
> +						   + add_col]) {
> +							ok = 0;
> +							break;
> +						}
> +					}
> +				}
> +
> +				/*
> +				 * Return 'middle' of rectangle in case of
> +				 * success
> +				 */
> +				if (ok) {
> +					if(rect_width > 1)
> +						rect_width--;
> +
> +					if(rect_height > 1)
> +						rect_height--;
> +
> +					*cal_row = start_row +
> +						   (rect_height / 2);
> +					*cal_col = start_col + (rect_width / 2);
> +
> +					return 0;
> +				}
> +			}
> +		}
> +	}
> +
> +	/* We could not fit any rectangle - return failure */
> +	return 1;

Oh btw. please make sure to use errno.h and standard return codes ; -EINVAL in 
this case I believe.