[U-Boot] [PATCH v2 1/2] arm: socfpga: mmc: Enable calibration for drvsel and smpsel

[Chin Liang See]

Hi guys,

Any comment or ack for this patch?
Thanks

Chin Liang

On Thu, 2015-08-20 at 02:18 -0500, 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: Stefan Roese <sr at denx.de>
> ---
> Changes for v2
> - Using standard error return macro
> - Split to small function to avoid deep identation
> - Fix coding standard
> ---
>  drivers/mmc/socfpga_dw_mmc.c |  194 ++++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 187 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/socfpga_dw_mmc.c b/drivers/mmc/socfpga_dw_mmc.c
> index eb69aed..0fbea49 100644
> --- a/drivers/mmc/socfpga_dw_mmc.c
> +++ b/drivers/mmc/socfpga_dw_mmc.c
> @@ -11,25 +11,147 @@
>  #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
> +
> +int find_row_col_fit_rectangle(unsigned rect_width, unsigned rect_height,
> +unsigned char cal_results[CAL_ROWS][CAL_COLS], unsigned int *cal_row,
> +unsigned int *cal_col)
> +{
> +	unsigned char start_row, start_col;
> +
> +	/* 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;
> +			}
> +		}
> +	}
> +	return -EINVAL;
> +}
> +
> +/*
> + * 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 */
> +	struct rect_cand_t {
> +		unsigned char height;
> +		unsigned char width;
> +		unsigned short area;
> +	};
> +
> +	/* Array with the rectangle candidates */
> +	struct rect_cand_t rect_cands[CAL_ROWS * CAL_COLS], tmp;
> +	unsigned char cr_rect_cand = 0;
> +	unsigned char height, width, k;
> +
> +	/* No solution if all combinations fail */
> +	if (sum == 0)
> +		return -EINVAL;
> +
> +	/* 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) {
> +					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++) {
> +		if (!find_row_col_fit_rectangle(rect_cands[k].width,
> +						rect_cands[k].height,
> +						cal_results, cal_row, cal_col))
> +			return 0;
> +	}
>  
> +	/* We could not fit any rectangle - return failure */
> +	return -EINVAL;
> +}
> +
> +void socfpga_dwmmc_set_clksel(unsigned int drvsel, unsigned int smplsel)
> +{
>  	/* Disable SDMMC clock. */
>  	clrbits_le32(&clock_manager_base->per_pll.en,
>  		CLKMGR_PERPLLGRP_EN_SDMMCCLK_MASK);
>  
> -	/* Configures drv_sel and smpl_sel */
> -	drvsel = CONFIG_SOCFPGA_DWMMC_DRVSEL;
> -	smplsel = CONFIG_SOCFPGA_DWMMC_SMPSEL;
> -
>  	debug("%s: drvsel %d smplsel %d\n", __func__, drvsel, smplsel);
>  	writel(SYSMGR_SDMMC_CTRL_SET(smplsel, drvsel),
>  		&system_manager_base->sdmmcgrp_ctrl);
> @@ -42,6 +164,64 @@ static void socfpga_dwmci_clksel(struct dwmci_host *host)
>  		CLKMGR_PERPLLGRP_EN_SDMMCCLK_MASK);
>  }
>  
> +/*
> + * This functions calirates the drvsel and smplsel by trying all possible
> + * values and selecting the best combnation
> + */
> +void socfpga_dwmmc_calibrate(struct dwmci_host *host)
> +{
> +	int err = 0;
> +	unsigned char cal_results[CAL_ROWS][CAL_COLS];
> +	unsigned int sum = 0;
> +	unsigned int row, col, drvsel, smplsel;
> +
> +	struct mmc *mmc = (struct mmc *)host->mmc;
> +	if (mmc == NULL) {
> +		printf("struct mmc is NULL\n");
> +		hang();
> +	}
> +
> +	printf("%s: Calibration started.\n", __func__);
> +
> +	for (row = 0; row < CAL_ROWS; row++) {
> +		for (col = 0; col < CAL_COLS; col++) {
> +			drvsel = row + 1;
> +			smplsel = col;
> +			socfpga_dwmmc_set_clksel(drvsel, smplsel);
> +			cal_results[row][col] = !(mmc_set_blocklen(mmc,
> +						  mmc->read_bl_len));
> +			sum += cal_results[row][col];
> +		}
> +	}
> +
> +	debug("%s: Calibration raw data:\n", __func__);
> +	for (row = 0; row < CAL_ROWS; row++) {
> +		debug("\t");
> +		for (col = 0; col < CAL_COLS; col++)
> +			debug("%d ", cal_results[row][col]);
> +		debug("\n");
> +	}
> +
> +	err = find_calibration_point(cal_results, sum, &drvsel, &smplsel);
> +
> +	if (err) {
> +		printf("%s: Calibration failed.\n", __func__);
> +		hang();
> +	} else
> +		printf("%s: Calibration passed: drvsel = %d "
> +		       "smplsel = %d.\n", __func__, drvsel, smplsel);
> +
> +	socfpga_dwmmc_set_clksel(drvsel, smplsel);
> +
> +	/* re-write in case accidentally overwrite with junk */
> +	mmc_set_blocklen(mmc, mmc->read_bl_len);
> +}
> +
> +void socfpga_dwmci_clksel(struct dwmci_host *host)
> +{
> +	socfpga_dwmmc_calibrate(host);
> +}
> +
>  int socfpga_dwmmc_init(u32 regbase, int bus_width, int index)
>  {
>  	struct dwmci_host *host;