[PATCH 1/5] mmc: am654_sdhci: Add tuning algorithm for delay chain
Jaehoon Chung
jh80.chung at samsung.com
Wed Apr 17 13:23:31 CEST 2024
> -----Original Message-----
> From: Judith Mendez <jm at ti.com>
> Sent: Tuesday, April 16, 2024 6:28 AM
> To: Peng Fan <peng.fan at nxp.com>; Jaehoon Chung <jh80.chung at samsung.com>; Tom Rini <trini at konsulko.com>
> Cc: Nitin Yadav <n-yadav at ti.com>; Simon Glass <sjg at chromium.org>; u-boot at lists.denx.de
> Subject: [PATCH 1/5] mmc: am654_sdhci: Add tuning algorithm for delay chain
>
> Currently the sdhci_am654 driver only supports one tuning
> algorithm which should be used only when DLL is enabled. The
> ITAPDLY is selected from the largest passing window and the
> buffer is viewed as a circular buffer.
>
> The new tuning algorithm should be used when the delay chain
> is enabled; the ITAPDLY is selected from the largest passing
> window and the buffer is not viewed as a circular buffer.
>
> This implementation is based off of the following paper: [1].
>
> Also add support for multiple failing windows.
>
> [1] https://www.ti.com/lit/an/spract9/spract9.pdf
>
> Fixes: a759abf569d4 ("mmc: am654_sdhci: Add support for software tuning")
> Signed-off-by: Judith Mendez <jm at ti.com>
> ---
> drivers/mmc/am654_sdhci.c | 107 +++++++++++++++++++++++++++++++-------
> 1 file changed, 89 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/mmc/am654_sdhci.c b/drivers/mmc/am654_sdhci.c
> index 05595bdac39..e5ad00e2531 100644
> --- a/drivers/mmc/am654_sdhci.c
> +++ b/drivers/mmc/am654_sdhci.c
> @@ -97,6 +97,7 @@ struct am654_sdhci_plat {
> u32 strb_sel;
> u32 clkbuf_sel;
> u32 flags;
> + bool dll_enable;
> #define DLL_PRESENT BIT(0)
> #define IOMUX_PRESENT BIT(1)
> #define FREQSEL_2_BIT BIT(2)
> @@ -110,6 +111,12 @@ struct timing_data {
> u32 capability;
> };
>
> +struct window {
> + u8 start;
> + u8 end;
> + u8 length;
> +};
> +
> static const struct timing_data td[] = {
> [MMC_LEGACY] = {"ti,otap-del-sel-legacy",
> "ti,itap-del-sel-legacy",
> @@ -280,8 +287,11 @@ static int am654_sdhci_set_ios_post(struct sdhci_host *host)
> ret = am654_sdhci_setup_dll(plat, speed);
> if (ret)
> return ret;
> +
> + plat->dll_enable = true;
> } else {
> am654_sdhci_setup_delay_chain(plat, mode);
> + plat->dll_enable = false;
> }
>
> regmap_update_bits(plat->base, PHY_CTRL5, CLKBUFSEL_MASK,
> @@ -375,38 +385,99 @@ static void am654_sdhci_write_b(struct sdhci_host *host, u8 val, int reg)
> writeb(val, host->ioaddr + reg);
> }
> #ifdef MMC_SUPPORTS_TUNING
> -#define ITAP_MAX 32
> +#define ITAPDLY_LENGTH 32
> +#define ITAPDLY_LAST_INDEX (ITAPDLY_LENGTH - 1)
> +
> +static u32 am654_sdhci_calculate_itap(struct udevice *dev, struct window
> + *fail_window, u8 num_fails, bool circular_buffer)
> +{
> + u8 itap = 0, start_fail = 0, end_fail = 0, pass_length = 0;
> + u8 first_fail_start = 0, last_fail_end = 0;
> + struct window pass_window = {0, 0, 0};
> + int prev_fail_end = -1;
> + u8 i;
> +
> + if (!num_fails)
> + return ITAPDLY_LAST_INDEX >> 1;
> +
> + if (fail_window->length == ITAPDLY_LENGTH) {
> + dev_err(dev, "No passing ITAPDLY, return 0\n");
> + return 0;
> + }
> +
> + first_fail_start = fail_window->start;
> + last_fail_end = fail_window[num_fails - 1].end;
> +
> + for (i = 0; i < num_fails; i++) {
> + start_fail = fail_window[i].start;
> + end_fail = fail_window[i].end;
> + pass_length = start_fail - (prev_fail_end + 1);
> +
> + if (pass_length > pass_window.length) {
> + pass_window.start = prev_fail_end + 1;
> + pass_window.length = pass_length;
> + }
> + prev_fail_end = end_fail;
> + }
> +
> + if (!circular_buffer)
> + pass_length = ITAPDLY_LAST_INDEX - last_fail_end;
> + else
> + pass_length = ITAPDLY_LAST_INDEX - last_fail_end + first_fail_start;
> +
> + if (pass_length > pass_window.length) {
> + pass_window.start = last_fail_end + 1;
> + pass_window.length = pass_length;
> + }
> +
> + if (!circular_buffer)
> + itap = pass_window.start + (pass_window.length >> 1);
> + else
> + itap = (pass_window.start + (pass_window.length >> 1)) % ITAPDLY_LENGTH;
> +
> + return (itap > ITAPDLY_LAST_INDEX) ? ITAPDLY_LAST_INDEX >> 1 : itap;
> +}
> +
> static int am654_sdhci_execute_tuning(struct mmc *mmc, u8 opcode)
> {
> struct udevice *dev = mmc->dev;
> struct am654_sdhci_plat *plat = dev_get_plat(dev);
> - int cur_val, prev_val = 1, fail_len = 0, pass_window = 0, pass_len;
> - u32 itap;
> + struct window fail_window[ITAPDLY_LENGTH];
> + u8 curr_pass, itap;
> + u8 fail_index = 0;
> + u8 prev_pass = 1;
> +
> + memset(fail_window, 0, sizeof(fail_window));
>
> /* Enable ITAPDLY */
> regmap_update_bits(plat->base, PHY_CTRL4, ITAPDLYENA_MASK,
> 1 << ITAPDLYENA_SHIFT);
>
> - for (itap = 0; itap < ITAP_MAX; itap++) {
> + for (itap = 0; itap < ITAPDLY_LENGTH; itap++) {
> am654_sdhci_write_itapdly(plat, itap);
>
> - cur_val = !mmc_send_tuning(mmc, opcode, NULL);
> - if (cur_val && !prev_val)
> - pass_window = itap;
> + curr_pass = !mmc_send_tuning(mmc, opcode, NULL);
It's changed to !mmc_send_tuing(mmc, opcode). Could you change this based on latest u-boot?
Sorry for bothering you.
commit a3b2786651c7 "mmc: Drop unused mmc_send_tuning() cmd_error parameter"
Best Regards,
Jaehoon Chung
>
> - if (!cur_val)
> - fail_len++;
> + if (!curr_pass && prev_pass)
> + fail_window[fail_index].start = itap;
>
> - prev_val = cur_val;
> + if (!curr_pass) {
> + fail_window[fail_index].end = itap;
> + fail_window[fail_index].length++;
> + }
> +
> + if (curr_pass && !prev_pass)
> + fail_index++;
> +
> + prev_pass = curr_pass;
> }
> - /*
> - * Having determined the length of the failing window and start of
> - * the passing window calculate the length of the passing window and
> - * set the final value halfway through it considering the range as a
> - * circular buffer
> - */
> - pass_len = ITAP_MAX - fail_len;
> - itap = (pass_window + (pass_len >> 1)) % ITAP_MAX;
> +
> + if (fail_window[fail_index].length != 0)
> + fail_index++;
> +
> + itap = am654_sdhci_calculate_itap(dev, fail_window, fail_index,
> + plat->dll_enable);
> +
> am654_sdhci_write_itapdly(plat, itap);
>
> return 0;
> --
> 2.43.2
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