On Thu, June 26, 2014, Doug Anderson wrote:
> Seungwon,
>
> On Wed, Jun 25, 2014 at 6:08 AM, Seungwon Jeon <tgih.jun@xxxxxxxxxxx> wrote:
> > On Mon, June 23, 2014, Yuvaraj Kumar C D wrote:
> >> Subject: [PATCH 3/3] mmc: dw_mmc: Support voltage changes
> >>
> >> From: Doug Anderson <dianders@xxxxxxxxxxxx>
> >>
> >> For UHS cards we need the ability to switch voltages from 3.3V to
> >> 1.8V. Add support to the dw_mmc driver to handle this. Note that
> >> dw_mmc needs a little bit of extra code since the interface needs a
> >> special bit programmed to the CMD register while CMD11 is progressing.
> >> This means adding a few extra states to the state machine to track.
> >
> > Overall new additional states makes it complicated.
> > Can we do that in other way?
>
> That was the best I was able to figure out when I thought this
> through. If you have ideas for doing it another way I'd imagine that
> Yuvaraj would be happy to take your feedback.
Let's clean up SDMMC_CMD_VOLT_SWITCH.
In turn, we may remove state-handling simply.
>
>
> >> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
> >> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@xxxxxxxxxxx>
> >>
> >> ---
> >> drivers/mmc/host/dw_mmc.c | 145 +++++++++++++++++++++++++++++++++++++++++---
> >> drivers/mmc/host/dw_mmc.h | 5 +-
> >> include/linux/mmc/dw_mmc.h | 2 +
> >> 3 files changed, 142 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> >> index e034bce..38eb548 100644
> >> --- a/drivers/mmc/host/dw_mmc.c
> >> +++ b/drivers/mmc/host/dw_mmc.c
> >> @@ -29,6 +29,7 @@
> >> #include <linux/irq.h>
> >> #include <linux/mmc/host.h>
> >> #include <linux/mmc/mmc.h>
> >> +#include <linux/mmc/sd.h>
> >> #include <linux/mmc/sdio.h>
> >> #include <linux/mmc/dw_mmc.h>
> >> #include <linux/bitops.h>
> >> @@ -235,10 +236,13 @@ err:
> >> }
> >> #endif /* defined(CONFIG_DEBUG_FS) */
> >>
> >> +static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg);
> >> +
> >> static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
> >> {
> >> struct mmc_data *data;
> >> struct dw_mci_slot *slot = mmc_priv(mmc);
> >> + struct dw_mci *host = slot->host;
> >> const struct dw_mci_drv_data *drv_data = slot->host->drv_data;
> >> u32 cmdr;
> >> cmd->error = -EINPROGRESS;
> >> @@ -254,6 +258,32 @@ static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command
> *cmd)
> >> else if (cmd->opcode != MMC_SEND_STATUS && cmd->data)
> >> cmdr |= SDMMC_CMD_PRV_DAT_WAIT;
> >>
> >> + if (cmd->opcode == SD_SWITCH_VOLTAGE) {
> >> + u32 clk_en_a;
> >> +
> >> + /* Special bit makes CMD11 not die */
> >> + cmdr |= SDMMC_CMD_VOLT_SWITCH;
> >> +
> >> + /* Change state to continue to handle CMD11 weirdness */
> >> + WARN_ON(slot->host->state != STATE_SENDING_CMD);
> >> + slot->host->state = STATE_SENDING_CMD11;
> >> +
> >> + /*
> >> + * We need to disable clock stop while doing voltage switch
> >> + * according to 7.4.1.2 Voltage Switch Normal Scenario.
> >> + *
> >> + * It's assumed that by the next time the CLKENA is updated
> >> + * (when we set the clock next) that the voltage change will
> >> + * be over, so we don't bother setting any bits to synchronize
> >> + * with dw_mci_setup_bus().
> >> + */
> >> + clk_en_a = mci_readl(host, CLKENA);
> >> + clk_en_a &= ~(SDMMC_CLKEN_LOW_PWR << slot->id);
> >> + mci_writel(host, CLKENA, clk_en_a);
> >> + mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
> >> + SDMMC_CMD_PRV_DAT_WAIT, 0);
> > dw_mci_disable_low_power() can be used here.
>
> Ah. I guess we don't have that locally anymore. Locally we have variants on:
I'm checking on cjb/mmc branch.
> * https://patchwork.kernel.org/patch/3070311/
> * https://patchwork.kernel.org/patch/3070251/
> * https://patchwork.kernel.org/patch/3070221/
>
> ...which removed that function. ...but I guess upstream never picked
> up those patches, huh? Looking back it looks like you had some
> feedback and it needed another spin but somehow fell off my plate. :(
>
> Maybe this is something Yuvaraj would like to pick up?
It's long ago. I remember that there is no progress since my last comment.
In case of patch "3070221", I want to pick up for next Kernel.
>
> >
> >> + }
> >> +
> >> if (cmd->flags & MMC_RSP_PRESENT) {
> >> /* We expect a response, so set this bit */
> >> cmdr |= SDMMC_CMD_RESP_EXP;
> >> @@ -776,11 +806,15 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
> >> unsigned int clock = slot->clock;
> >> u32 div;
> >> u32 clk_en_a;
> >> + u32 sdmmc_cmd_bits = SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT;
> >> +
> >> + /* We must continue to set bit 28 in CMD until the change is complete */
> >> + if (host->state == STATE_WAITING_CMD11_DONE)
> >> + sdmmc_cmd_bits |= SDMMC_CMD_VOLT_SWITCH;
> > I didn't get the reason SDMMC_CMD_VOLT_SWITCH is needed during clock update(enable/disable)
> > Can you explain it in details?
>
> Simply put: if I didn't do this then the system hung during voltage
> switch. It was not documented in the version of the IP manual that I
> had access to and it took me a bunch of digging / trial and error to
> figure this out. Whatever this bit does internally it's important to
> set it while the voltage change is happening. Note that this need was
> the whole reason for adding the extra state to the state machine.
>
> Perhaps Yuvaraj can try without it and I'd assume he'll report the
> same freeze.
Clarify the necessity of SDMMC_CMD_VOLT_SWITCH.
As far as I experience, we didn't apply this bit for several projects.
>
>
> >> if (!clock) {
> >> mci_writel(host, CLKENA, 0);
> >> - mci_send_cmd(slot,
> >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> >> + mci_send_cmd(slot, sdmmc_cmd_bits, 0);
> >> } else if (clock != host->current_speed || force_clkinit) {
> >> div = host->bus_hz / clock;
> >> if (host->bus_hz % clock && host->bus_hz > clock)
> >> @@ -804,15 +838,13 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
> >> mci_writel(host, CLKSRC, 0);
> >>
> >> /* inform CIU */
> >> - mci_send_cmd(slot,
> >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> >> + mci_send_cmd(slot, sdmmc_cmd_bits, 0);
> >>
> >> /* set clock to desired speed */
> >> mci_writel(host, CLKDIV, div);
> >>
> >> /* inform CIU */
> >> - mci_send_cmd(slot,
> >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> >> + mci_send_cmd(slot, sdmmc_cmd_bits, 0);
> >>
> >> /* enable clock; only low power if no SDIO */
> >> clk_en_a = SDMMC_CLKEN_ENABLE << slot->id;
> >> @@ -821,8 +853,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
> >> mci_writel(host, CLKENA, clk_en_a);
> >>
> >> /* inform CIU */
> >> - mci_send_cmd(slot,
> >> - SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
> >> + mci_send_cmd(slot, sdmmc_cmd_bits, 0);
> >>
> >> /* keep the clock with reflecting clock dividor */
> >> slot->__clk_old = clock << div;
> >> @@ -898,6 +929,17 @@ static void dw_mci_queue_request(struct dw_mci *host, struct dw_mci_slot *slot,
> >>
> >> slot->mrq = mrq;
> >>
> >> + if (host->state == STATE_WAITING_CMD11_DONE) {
> >> + dev_warn(&slot->mmc->class_dev,
> >> + "Voltage change didn't complete\n");
> >> + /*
> >> + * this case isn't expected to happen, so we can
> >> + * either crash here or just try to continue on
> >> + * in the closest possible state
> >> + */
> >> + host->state = STATE_IDLE;
> >> + }
> >> +
> >> if (host->state == STATE_IDLE) {
> >> host->state = STATE_SENDING_CMD;
> >> dw_mci_start_request(host, slot);
> >> @@ -993,6 +1035,9 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >> /* Slot specific timing and width adjustment */
> >> dw_mci_setup_bus(slot, false);
> >>
> >> + if (slot->host->state == STATE_WAITING_CMD11_DONE && ios->clock != 0)
> >> + slot->host->state = STATE_IDLE;
> >> +
> >> switch (ios->power_mode) {
> >> case MMC_POWER_UP:
> >> if ((!IS_ERR(mmc->supply.vmmc)) &&
> >> @@ -1039,6 +1084,68 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> >> }
> >> }
> >>
> >> +static int dw_mci_card_busy(struct mmc_host *mmc)
> >> +{
> >> + struct dw_mci_slot *slot = mmc_priv(mmc);
> >> + u32 status;
> >> +
> >> + /*
> >> + * Check the busy bit which is low when DAT[3:0]
> >> + * (the data lines) are 0000
> >> + */
> >> + status = mci_readl(slot->host, STATUS);
> >> +
> >> + return !!(status & SDMMC_STATUS_BUSY);
> >> +}
> >> +
> >> +static int dw_mci_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios)
> >> +{
> >> + struct dw_mci_slot *slot = mmc_priv(mmc);
> >> + struct dw_mci *host = slot->host;
> >> + u32 uhs;
> >> + u32 v18 = SDMMC_UHS_18V << slot->id;
> >> + int min_uv, max_uv;
> >> + int ret;
> >> +
> >> + /*
> >> + * Program the voltage. Note that some instances of dw_mmc may use
> >> + * the UHS_REG for this. For other instances (like exynos) the UHS_REG
> >> + * does no harm but you need to set the regulator directly. Try both.
> >> + */
> >> + uhs = mci_readl(host, UHS_REG);
> >> + if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
> >> + min_uv = 2700000;
> >> + max_uv = 3600000;
> >> + uhs &= ~v18;
> >> + } else {
> >> + min_uv = 1700000;
> >> + max_uv = 1950000;
> >> + uhs |= v18;
> >> + }
> >> + if (!IS_ERR(mmc->supply.vqmmc)) {
> >> + ret = regulator_set_voltage(mmc->supply.vqmmc, min_uv, max_uv);
> >> +
> >> + /*
> >> + * Only complain if regulator claims that it's not in the 1.8V
> >> + * range. This avoids a bunch of errors in the case that
> >> + * we've got a fixed 1.8V regulator but the core SD code still
> >> + * thinks it ought to try to switch to 3.3 and then back to 1.8
> >> + */
> >> + if (ret) {
> > I think if ret is error, printing message and returning error is good.
> > Currently, just returning '0' though it fails.
Any feedback?
> >
> >> + int cur_voltage = 0;
> >> +
> >> + cur_voltage = regulator_get_voltage(mmc->supply.vqmmc);
> >> + if (cur_voltage < 1700000 || cur_voltage > 1950000)
> >> + dev_warn(&mmc->class_dev,
> >> + "Regulator set error %d: %d - %d\n",
> >> + ret, min_uv, max_uv);
> >> + }
> >> + }
> >> + mci_writel(host, UHS_REG, uhs);
> >> +
> >> + return 0;
> >> +}
> >> +
> >> static int dw_mci_get_ro(struct mmc_host *mmc)
> >> {
> >> int read_only;
> >> @@ -1180,6 +1287,9 @@ static const struct mmc_host_ops dw_mci_ops = {
> >> .get_cd = dw_mci_get_cd,
> >> .enable_sdio_irq = dw_mci_enable_sdio_irq,
> >> .execute_tuning = dw_mci_execute_tuning,
> >> + .card_busy = dw_mci_card_busy,
> >> + .start_signal_voltage_switch = dw_mci_switch_voltage,
> >> +
> >> };
> >>
> >> static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
> >> @@ -1203,7 +1313,11 @@ static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
> >> dw_mci_start_request(host, slot);
> >> } else {
> >> dev_vdbg(host->dev, "list empty\n");
> >> - host->state = STATE_IDLE;
> >> +
> >> + if (host->state == STATE_SENDING_CMD11)
> >> + host->state = STATE_WAITING_CMD11_DONE;
> >> + else
> >> + host->state = STATE_IDLE;
> >> }
> >>
> >> spin_unlock(&host->lock);
> >> @@ -1314,8 +1428,10 @@ static void dw_mci_tasklet_func(unsigned long priv)
> >>
> >> switch (state) {
> >> case STATE_IDLE:
> >> + case STATE_WAITING_CMD11_DONE:
> >> break;
> >>
> >> + case STATE_SENDING_CMD11:
> >> case STATE_SENDING_CMD:
> >> if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
> >> &host->pending_events))
> >> @@ -1870,6 +1986,15 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
> >> }
> >>
> >> if (pending) {
> >> + /* Check volt switch first, since it can look like an error */
> >> + if ((host->state == STATE_SENDING_CMD11) &&
> >> + (pending & SDMMC_INT_VOLT_SWITCH)) {
> >> + mci_writel(host, RINTSTS, SDMMC_INT_VOLT_SWITCH);
> >> + pending &= ~SDMMC_INT_VOLT_SWITCH;
> >> + dw_mci_cmd_interrupt(host,
> >> + pending | SDMMC_INT_CMD_DONE);
> > Artificially adding SDMMC_INT_CMD_DONE to pending is needed to complete cmd handling?
> > Is there any reason?
>
> I don't remember this for sure since I wrote this a long time ago.
> Maybe it's not needed? I may have just been modeling on other
> interrupts.
If there is no specific reason, please remove it.
Thanks,
Seungwon Jeon
>
> -Doug
> --
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