[PATCH 1/5] mmc: am654_sdhci: Add tuning algorithm for delay chain
Judith Mendez
jm at ti.com
Thu Apr 18 16:28:39 CEST 2024
Hi,
On 4/17/24 6:23 AM, Jaehoon Chung wrote:
>
>
>> -----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"
Thanks, will fix.
~ Judith
>
> 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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