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

Dinh Nguyen
2015-08-20T21:55:02Z

+CC: Simon Glass

On Thu, Aug 20, 2015 at 12:32 AM, Marek Vasut <marex@denx.de> wrote:
> On Thursday, August 20, 2015 at 07:28:02 AM, Chin Liang See wrote:
>> Hi,
>>
>> On Wed, 2015-08-19 at 14:36 +0000, marex at denx.de wrote:
>> > On Wednesday, August 19, 2015 at 10:21:17 AM, Chin Liang See wrote:
>> > > Hi,
>> >
>> > Hi again,
>> >
>> > > On Wed, 2015-08-19 at 02:41 +0000, marex at denx.de wrote:
>> > > > 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@altera.com>
>> > > > > Cc: Dinh Nguyen <dinguyen@opensource.altera.com>

I think there's something wrong with your git scripts, I did not get this email.

>> > > > > 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/18441
>> > > > > 0529 + * 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.
>> > >
>> > > Good suggestion, will fix in v2.
>> > > Thanks
>> >
>> > Thanks. I was curious, is this really socfpga specific or can this
>> > calibration be used on dwmmc in general -- thus on exynos and rockchip
>> > systems -- as well? If it's generic to dwmmc, this should be moved into
>> > the dwmmc core code. Also, I am CCing Simon, he's been plumbing in the
>> > DWMMC recently.

I didn't see you explicitly add Simon to the thread. Doing it here..

>>
>> I am not sure. But definitely we can make the calibration common enough
>> if they required the calibration too. Let wait feedback from Simon.
>

I know that the linux driver for the DW MMC for SoCFGPA, Exynos and Rockchip
are using the drvsel and smpsel parameters. But I also think these
parameters can
be different for different types of SD card. Are you sure this
function will cover those
cases?

Dinh