[U-Boot] [PATCH v4] mmc: socfpga_dw_mmc: Enable calibration for drvsel and smplsel

[Marek Vasut <marex@denx.de>]

On Friday, November 27, 2015 at 08:22:03 AM, Chin Liang See wrote:
> Enable SDMMC calibration to determine the best setting for
> drvsel and smplsel. Calibration will be triggered if the
> drvsel and smplsel node are not available in DTS.
> 
> Signed-off-by: Chin Liang See <clsee@altera.com>
> Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
> Cc: Dinh Nguyen <dinh.linux@gmail.com>
> Cc: Pavel Machek <pavel@denx.de>
> Cc: Marek Vasut <marex@denx.de>
> Cc: Stefan Roese <sr@denx.de>
> Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> Cc: Simon Glass <sjg@chromium.org>
> Cc: Jaehoon Chung <jh80.chung@samsung.com>
> ---
> Changes for v4
> - Calibration only run if node not in DTS
> Changes for v3
> - Remove the && ok as its redundant
> 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 | 208
> ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 205
> insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/socfpga_dw_mmc.c b/drivers/mmc/socfpga_dw_mmc.c
> index 2bd0ebd..a8e2660 100644
> --- a/drivers/mmc/socfpga_dw_mmc.c
> +++ b/drivers/mmc/socfpga_dw_mmc.c
> @@ -13,6 +13,7 @@
>  #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;
> @@ -25,7 +26,144 @@ struct dwmci_socfpga_priv_data {
>  	unsigned int smplsel;
>  };
> 
> -static void socfpga_dwmci_clksel(struct dwmci_host *host)
> +/*
> + * rows and columns of calibration rectange. The values are based on the
> value + * range of drvsel and smplsel register in system manager. Note
> drvsel 0 is + * unusable as it has meta-stability issue.
> + */
> +#define SOCFPGA_SD_DRVSEL  7
> +#define SOCFPGA_SD_SMPLSEL 8
> +
> +static int socfpga_dwmci_find_row_col_fit_rectangle(unsigned rect_width,
> +	unsigned rect_height,
> +	unsigned char cal_results[SOCFPGA_SD_DRVSEL][SOCFPGA_SD_SMPLSEL],
> +	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 < (SOCFPGA_SD_SMPLSEL - rect_width + 1);
> +	     start_col++) {
> +		for (start_row = 0;
> +		     start_row < (SOCFPGA_SD_DRVSEL - 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); 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
> +			 */

I think you can refactor this indentation horror some more, right ?

> +			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;

For example this condition can be inverted and it'd shave off one level
of indent.

> +			}
> +		}
> +	}
> +	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.
> + */
> +static int socfpga_dwmci_find_calibration_point(
> +	unsigned char cal_results[SOCFPGA_SD_DRVSEL][SOCFPGA_SD_SMPLSEL],
> +	unsigned int sum, unsigned int *cal_row, unsigned int *cal_col)
> +{
> +	/* 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[SOCFPGA_SD_DRVSEL * SOCFPGA_SD_SMPLSEL];
> +	struct rect_cand_t 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 == (SOCFPGA_SD_DRVSEL * SOCFPGA_SD_SMPLSEL)) {
> +		*cal_row = (SOCFPGA_SD_DRVSEL - 1) / 2;
> +		*cal_col = (SOCFPGA_SD_SMPLSEL - 1) / 2;
> +		return 0;
> +	}
> +
> +	/*
> +	 * Create list of all possible sub-rectangles, in descending area
> +	 * order
> +	 */
> +	for (height = SOCFPGA_SD_DRVSEL; height >= 1; height--) {
> +		for (width = SOCFPGA_SD_SMPLSEL; 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;

Indent here as well ...
if (!cond)
 break;

do your job here.

> +				}
> +			}
> +		}
> +	}
> +
> +	/* Try to fit the rectangle candidates, in descending area order */
> +	for (k = 0; k < SOCFPGA_SD_DRVSEL * SOCFPGA_SD_SMPLSEL; k++) {
> +		if (!socfpga_dwmci_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;
> +}
> +
> +static void socfpga_dwmci_set_clksel(struct dwmci_host *host)
>  {
>  	struct dwmci_socfpga_priv_data *priv = host->priv;
> 

[...]

>  static int socfpga_dwmci_of_probe(const void *blob, int node, const int
> idx) {
>  	/* FIXME: probe from DT eventually too/ */
> @@ -102,8 +304,8 @@ static int socfpga_dwmci_of_probe(const void *blob, int
> node, const int idx) host->bus_hz = clk;
>  	host->fifoth_val = MSIZE(0x2) |
>  		RX_WMARK(fifo_depth / 2 - 1) | TX_WMARK(fifo_depth / 2);
> -	priv->drvsel = fdtdec_get_uint(blob, node, "drvsel", 3);
> -	priv->smplsel = fdtdec_get_uint(blob, node, "smplsel", 0);
> +	priv->drvsel = fdtdec_get_uint(blob, node, "drvsel", 0xf);
> +	priv->smplsel = fdtdec_get_uint(blob, node, "smplsel", 0xf);

This breaks multiple boards, since it misconfigures the default values.

>  	host->priv = priv;
> 
>  	return add_dwmci(host, host->bus_hz, 400000);