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

[Pavel Machek <pavel@denx.de>]

On Wed 2015-08-19 00:54:50, 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@altera.com>
> Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
> Cc: Pavel Machek <pavel@denx.de>
> Cc: Marek Vasut <marex@denx.de>
> Cc: Wolfgang Denk <wd@denx.de>
> Cc: Stefan Roese <sr@denx.de>
> Cc: Tom Rini <trini@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

Actually, I'd like to see optimized version.  It has potential to be
easier to read...

> + * 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;

Codingstyle: "if ("

> +	/*
> +	 * 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--){

No space before ;.


> +	/* 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;

Create separate functions to make it easier to read and less indented.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html