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Message-ID: <c544867e-7ba5-1bdf-50ae-b26b634676ed@intel.com>
Date: Fri, 26 Jan 2018 10:00:58 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: "ernest.zhang" <ernest.zhang@...hubtech.com>,
ulf.hansson@...aro.org, linux-mmc@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: shirley.her@...hubtech.com, yuxiang.wan@...hubtech.com,
xiaoguang.yu@...hubtech.com
Subject: Re: [PATCH 2/2] mmc: sdhci: Add support for O2 hardware tuning
On 17/01/18 03:38, ernest.zhang wrote:
> O2 sd host controllers have a hardware tuning function. In software
> tuning mode CPU should send multiple command to host controller but in
> hardware tuning mode, CPU need send only one tuning command to sd host
> controller. It can improve the speed linux boot from eMMC.
>
> Signed-off-by: ernest.zhang <ernest.zhang@...hubtech.com>
Please use version numbers in the patch subject. This was V3, the next is
V4. A summary of what has changed (after the --- line or in the cover email)
is also expected.
> ---
> drivers/mmc/host/sdhci-pci-o2micro.c | 193 +++++++++++++++++++++++++++++++++++
> drivers/mmc/host/sdhci.c | 5 +-
> 2 files changed, 197 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c
> index 8855a416ffd4..5978ead34827 100644
> --- a/drivers/mmc/host/sdhci-pci-o2micro.c
> +++ b/drivers/mmc/host/sdhci-pci-o2micro.c
> @@ -17,6 +17,12 @@
> */
>
> #include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/fixed.h>
> +#include <linux/regulator/machine.h>
> +#include <linux/mmc/host.h>
> +#include <linux/mmc/mmc.h>
> +#include <linux/delay.h>
>
> #include "sdhci.h"
> #include "sdhci-pci.h"
> @@ -57,6 +63,192 @@
> #define O2_SD_VENDOR_SETTING2 0x1C8
> #define O2_SD_HW_TUNING_ENABLE BIT(4)
>
> +static void sdhci_o2_start_tuning(struct sdhci_host *host)
> +{
> + u16 ctrl;
> +
> + ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> + ctrl |= SDHCI_CTRL_EXEC_TUNING;
> + sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +
> + /*
> + * As per the Host Controller spec v3.00, tuning command
> + * generates Buffer Read Ready interrupt, so enable that.
> + *
> + * Note: The spec clearly says that when tuning sequence
> + * is being performed, the controller does not generate
> + * interrupts other than Buffer Read Ready interrupt. But
> + * to make sure we don't hit a controller bug, we _only_
> + * enable Buffer Read Ready interrupt here.
> + */
> + sdhci_writel(host, SDHCI_INT_DATA_AVAIL, SDHCI_INT_ENABLE);
> + sdhci_writel(host, SDHCI_INT_DATA_AVAIL, SDHCI_SIGNAL_ENABLE);
> +}
> +
> +static void sdhci_o2_end_tuning(struct sdhci_host *host)
> +{
> + sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
> + sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
> +}
> +
> +static inline bool sdhci_data_line_cmd(struct mmc_command *cmd)
> +{
> + return cmd->data || cmd->flags & MMC_RSP_BUSY;
> +}
> +
> +static void sdhci_del_timer(struct sdhci_host *host, struct mmc_request *mrq)
> +{
> + if (sdhci_data_line_cmd(mrq->cmd))
> + del_timer(&host->data_timer);
> + else
> + del_timer(&host->timer);
> +}
> +
> +static void sdhci_o2_set_tuning_mode(struct sdhci_host *host)
> +{
> + u16 reg;
> +
> + /* enable hardware tuning */
> + reg = sdhci_readw(host, O2_SD_VENDOR_SETTING);
> + reg &= ~O2_SD_HW_TUNING_ENABLE;
> + sdhci_writew(host, reg, O2_SD_VENDOR_SETTING);
> +}
> +
> +
> +static int sdhci_o2_send_tuning(struct sdhci_host *host, u32 opcode)
> +{
> + struct mmc_command cmd = { };
> + struct mmc_data data = { };
> + struct scatterlist sg;
> + struct mmc_request mrq = { };
> + unsigned long flags;
> + u32 b = host->sdma_boundary;
> + int size = 64;
> + u8 *data_buf = kzalloc(size, GFP_KERNEL);
> +
> + if (!data_buf)
> + return -ENOMEM;
> +
> + cmd.opcode = opcode;
> + cmd.flags = MMC_RSP_PRESENT | MMC_RSP_OPCODE | MMC_RSP_CRC;
> + cmd.mrq = &mrq;
> + cmd.data = NULL;
I am confused now. If you set cmd.data to NULL then there is no point in
having struct mmc_data data at all.
But that also means my comment about not needing
SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD was wrong.
Please clarify.
> + mrq.cmd = &cmd;
> + mrq.data = &data;
> + data.blksz = size;
> + data.blocks = 1;
> + data.flags = MMC_DATA_READ;
> +
> + data.timeout_ns = 50 * NSEC_PER_MSEC;
> +
> + data.sg = &sg;
> + data.sg_len = 1;
> + sg_init_one(&sg, data_buf, size);
> +
> + spin_lock_irqsave(&host->lock, flags);
> +
> + sdhci_writew(host, SDHCI_MAKE_BLKSZ(b, 64), SDHCI_BLOCK_SIZE);
> +
> + /*
> + * The tuning block is sent by the card to the host controller.
> + * So we set the TRNS_READ bit in the Transfer Mode register.
> + * This also takes care of setting DMA Enable and Multi Block
> + * Select in the same register to 0.
> + */
So with no cmd.data then you can set the transfer mode, except that
SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD clears it again. Doesn't
SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD also cause a problem with SD
card tuning i.e. when you call sdhci_execute_tuning() ?
> + sdhci_send_command(host, &cmd);
> +
> + host->cmd = NULL;
> +
> + sdhci_del_timer(host, &mrq);
> +
> + host->tuning_done = 0;
> +
> + mmiowb();
> + spin_unlock_irqrestore(&host->lock, flags);
> +
> + /* Wait for Buffer Read Ready interrupt */
> + wait_event_timeout(host->buf_ready_int, (host->tuning_done == 1),
> + msecs_to_jiffies(50));
> + kfree(data_buf);
> + return 0;
> +}
> +
> +static void sdhci_o2_reset_tuning(struct sdhci_host *host)
> +{
> + u16 ctrl;
> +
> + ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> + ctrl &= ~SDHCI_CTRL_TUNED_CLK;
> + ctrl &= ~SDHCI_CTRL_EXEC_TUNING;
> + sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +}
> +
> +static void __sdhci_o2_execute_tuning(struct sdhci_host *host, u32 opcode)
> +{
> + int i;
> +
> + sdhci_o2_send_tuning(host, MMC_SEND_TUNING_BLOCK_HS200);
> +
> + for (i = 0; i < 150; i++) {
> + u16 ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +
> + if (!(ctrl & SDHCI_CTRL_EXEC_TUNING)) {
> + if (ctrl & SDHCI_CTRL_TUNED_CLK) {
> + host->tuning_done = true;
> + return;
> + }
> + pr_warn("%s: HW tuning failed !\n",
> + mmc_hostname(host->mmc));
> + break;
> + }
> +
> + mdelay(1);
> + }
> +
> + pr_info("%s: Tuning failed, falling back to fixed sampling clock\n",
> + mmc_hostname(host->mmc));
> + sdhci_o2_reset_tuning(host);
> +}
> +
> +static int sdhci_o2_execute_tuning(struct mmc_host *mmc, u32 opcode)
> +{
> + struct sdhci_host *host = mmc_priv(mmc);
> + int current_bus_width = 0;
> +
> + /*
> + * This handler only implements the eMMC tuning that is specific to
> + * this controller. Fall back to the standard method for other TIMING.
> + */
> + if (host->timing != MMC_TIMING_MMC_HS200)
> + return sdhci_execute_tuning(mmc, opcode);
> +
> + if (WARN_ON(opcode != MMC_SEND_TUNING_BLOCK_HS200))
> + return -EINVAL;
> +
> + /*
> + * o2 sdhci host didn't support 8bit emmc tuning
> + */
> + if (mmc->ios.bus_width == MMC_BUS_WIDTH_8) {
> + current_bus_width = mmc->ios.bus_width;
> + sdhci_set_bus_width(host, MMC_BUS_WIDTH_4);
> + }
> +
> + sdhci_o2_set_tuning_mode(host);
> +
> + sdhci_o2_start_tuning(host);
> +
> + __sdhci_o2_execute_tuning(host, opcode);
> +
> + sdhci_o2_end_tuning(host);
> +
> + if (current_bus_width == MMC_BUS_WIDTH_8) {
> + sdhci_set_bus_width(host, current_bus_width);
> + }
Unnecessary {}
> +
> + host->flags &= ~SDHCI_HS400_TUNING;
> + return 0;
> +}
> +
> static void o2_pci_set_baseclk(struct sdhci_pci_chip *chip, u32 value)
> {
> u32 scratch_32;
> @@ -214,6 +406,7 @@ int sdhci_pci_o2_probe_slot(struct sdhci_pci_slot *slot)
> }
> }
>
> + host->mmc_host_ops.execute_tuning = sdhci_o2_execute_tuning;
>
> if (chip->pdev->device != PCI_DEVICE_ID_O2_FUJIN2)
> break;
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index e9290a3439d5..8ed7afc84f7a 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -919,7 +919,10 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
> if (data == NULL) {
> if (host->quirks2 &
> SDHCI_QUIRK2_CLEAR_TRANSFERMODE_REG_BEFORE_CMD) {
> - sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
> + /* must not clear SDHCI_TRANSFER_MODE when tuning */
> + if (cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200) {
> + sdhci_writew(host, 0x0, SDHCI_TRANSFER_MODE);
> + }
> } else {
> /* clear Auto CMD settings for no data CMDs */
> mode = sdhci_readw(host, SDHCI_TRANSFER_MODE);
>
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