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

[Chin Liang See <clsee@altera.com>]

On Fri, 2015-08-21 at 14:52 -0600, Simon Glass wrote:
> Hi,
> 
> On 20 August 2015 at 15:55, Dinh Nguyen <dinh.linux@gmail.com> wrote:
> > +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..
> 
> One option is to put the function in the common dw_mmc.c file but have
> it be called explicitly by drivers that want it (e.g. for now, just
> socfpga). The code you have written does look generic and perhaps
> should be used on other platforms,
> 
> >
> >>>
> >>> 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?
> 
> Not at all, but perhaps that is something we will find out in the future.
> 

Thanks Simon.

I further checked today and noticed Exynos is setting up the clksel
(sample clock and drive clock). But from exynos_dw_mmc.c, the value is
coming from device tree. So I am notifying Jaehoon wonder the
calibration might applicable for him. 

Jaehoon, this patch will do a calibration to determine the clksel value.
Wonder is this something would help or applicable for Exynos? We are
probing whether this code should go dw_mmc.c instead socfpga_dw_mmc.c.

Thanks
Chin Liang

> Regards,
> Simon