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Date: Tue, 21 Dec 2021 10:41:49 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Ricky WU <ricky_wu@...ltek.com>
Cc: "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: rtsx: improve performance for multi block rw
On Thu, 9 Dec 2021 at 08:33, Ricky WU <ricky_wu@...ltek.com> wrote:
>
> Improving performance for the CMD is multi-block read/write
> and the data is sequential.
> sd_check_multi_seq() to distinguish multi-block RW (CMD 18/25)
> or normal RW (CMD 17/24) if the CMD is multi-block and the data is
> sequential then call to sd_rw_multi_seq()
This still doesn't explain what the change really does. How, exactly,
do you improve performance? Are you skipping some commands to be sent
or is the improvement solely based upon how the SD/(e)MMC card behaves
internally?
Of course, I can read the code below and I have a reasonably good idea
of what you want to do. However, the level of complexity for the new
code deserves a better description. Moreover, there is not a single
line of comment being added along the new code, so it's not always
obvious what goes on.
Finally, it would be nice to understand how much of improvement you
get with this change. I suggest you run some benchmarking tool, before
and after the change and provide that data as a part of the commit
message too.
Kind regards
Uffe
>
> Signed-off-by: Ricky Wu <ricky_wu@...ltek.com>
> ---
> v2:
> make commit message more clarity
> change function name for more clarity
> ---
> drivers/mmc/host/rtsx_pci_sdmmc.c | 185 +++++++++++++++++++++++++++++-
> 1 file changed, 180 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
> index 58cfaffa3c2d..ee2b0eec6422 100644
> --- a/drivers/mmc/host/rtsx_pci_sdmmc.c
> +++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
> @@ -22,6 +22,8 @@
> #include <asm/unaligned.h>
> #include <linux/pm_runtime.h>
>
> +enum RW_MODE {NORMAL_RW, SEQ_RW};
> +
> struct realtek_pci_sdmmc {
> struct platform_device *pdev;
> struct rtsx_pcr *pcr;
> @@ -31,6 +33,7 @@ struct realtek_pci_sdmmc {
>
> struct work_struct work;
> struct mutex host_mutex;
> + struct delayed_work rw_idle_work;
>
> u8 ssc_depth;
> unsigned int clock;
> @@ -46,6 +49,12 @@ struct realtek_pci_sdmmc {
> s32 cookie;
> int cookie_sg_count;
> bool using_cookie;
> +
> + enum RW_MODE rw_mode;
> + u8 prev_dir;
> + u8 cur_dir;
> + u64 prev_sec_addr;
> + u32 prev_sec_cnt;
> };
>
> static int sdmmc_init_sd_express(struct mmc_host *mmc, struct mmc_ios *ios);
> @@ -226,6 +235,14 @@ static void sd_send_cmd_get_rsp(struct realtek_pci_sdmmc *host,
> dev_dbg(sdmmc_dev(host), "%s: SD/MMC CMD %d, arg = 0x%08x\n",
> __func__, cmd_idx, arg);
>
> + if (cmd_idx == MMC_SEND_STATUS && host->rw_mode == SEQ_RW) {
> + cmd->resp[0] = R1_READY_FOR_DATA | (R1_STATE_TRAN << 9);
> + goto out;
> + }
> +
> + if (!mmc_op_multi(cmd->opcode))
> + host->rw_mode = NORMAL_RW;
> +
> rsp_type = sd_response_type(cmd);
> if (rsp_type < 0)
> goto out;
> @@ -542,6 +559,93 @@ static int sd_write_long_data(struct realtek_pci_sdmmc *host,
> return 0;
> }
>
> +static int sd_rw_multi_seq(struct realtek_pci_sdmmc *host, struct mmc_request *mrq)
> +{
> + struct rtsx_pcr *pcr = host->pcr;
> + struct mmc_host *mmc = host->mmc;
> + struct mmc_card *card = mmc->card;
> + struct mmc_data *data = mrq->data;
> + int uhs = mmc_card_uhs(card);
> + u8 cfg2;
> + int err;
> + size_t data_len = data->blksz * data->blocks;
> +
> + cfg2 = SD_NO_CALCULATE_CRC7 | SD_CHECK_CRC16 |
> + SD_NO_WAIT_BUSY_END | SD_NO_CHECK_CRC7 | SD_RSP_LEN_0;
> +
> + if (!uhs)
> + cfg2 |= SD_NO_CHECK_WAIT_CRC_TO;
> +
> + rtsx_pci_init_cmd(pcr);
> + sd_cmd_set_data_len(pcr, data->blocks, data->blksz);
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, IRQSTAT0,
> + DMA_DONE_INT, DMA_DONE_INT);
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, DMATC3,
> + 0xFF, (u8)(data_len >> 24));
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, DMATC2,
> + 0xFF, (u8)(data_len >> 16));
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, DMATC1,
> + 0xFF, (u8)(data_len >> 8));
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, DMATC0, 0xFF, (u8)data_len);
> +
> + if (host->cur_dir == DMA_DIR_FROM_CARD)
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, DMACTL,
> + 0x03 | DMA_PACK_SIZE_MASK,
> + DMA_DIR_FROM_CARD | DMA_EN | DMA_512);
> + else
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, DMACTL,
> + 0x03 | DMA_PACK_SIZE_MASK,
> + DMA_DIR_TO_CARD | DMA_EN | DMA_512);
> +
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, CARD_DATA_SOURCE,
> + 0x01, RING_BUFFER);
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SD_CFG2, 0xFF, cfg2);
> +
> + if (host->cur_dir == DMA_DIR_FROM_CARD)
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SD_TRANSFER, 0xFF,
> + SD_TRANSFER_START | SD_TM_AUTO_READ_3);
> + else
> + rtsx_pci_add_cmd(pcr, WRITE_REG_CMD, SD_TRANSFER, 0xFF,
> + SD_TRANSFER_START | SD_TM_AUTO_WRITE_3);
> +
> + rtsx_pci_add_cmd(pcr, CHECK_REG_CMD, SD_TRANSFER,
> + SD_TRANSFER_END, SD_TRANSFER_END);
> + rtsx_pci_send_cmd_no_wait(pcr);
> +
> + if (host->cur_dir == DMA_DIR_FROM_CARD)
> + err = rtsx_pci_dma_transfer(pcr, data->sg, host->sg_count, 1, 10000);
> + else
> + err = rtsx_pci_dma_transfer(pcr, data->sg, host->sg_count, 0, 10000);
> +
> + if (err < 0) {
> + sd_clear_error(host);
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +static int sd_stop_rw_multi_seq(struct realtek_pci_sdmmc *host, struct mmc_request *mrq)
> +{
> + struct rtsx_pcr *pcr = host->pcr;
> + struct mmc_command *cmd;
> +
> + cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
> +
> + cmd->opcode = MMC_STOP_TRANSMISSION;
> + cmd->arg = 0;
> + cmd->busy_timeout = 0;
> + if (host->cur_dir == DMA_DIR_FROM_CARD)
> + cmd->flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
> + else
> + cmd->flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
> + sd_send_cmd_get_rsp(host, cmd);
> + udelay(50);
> + rtsx_pci_write_register(pcr, RBCTL, RB_FLUSH, RB_FLUSH);
> + kfree(cmd);
> + return 0;
> +}
> +
> static inline void sd_enable_initial_mode(struct realtek_pci_sdmmc *host)
> {
> rtsx_pci_write_register(host->pcr, SD_CFG1,
> @@ -796,6 +900,45 @@ static inline int sd_rw_cmd(struct mmc_command *cmd)
> (cmd->opcode == MMC_WRITE_BLOCK);
> }
>
> +static void sd_rw_idle_work(struct work_struct *work)
> +{
> + struct delayed_work *dwork = to_delayed_work(work);
> + struct realtek_pci_sdmmc *host = container_of(dwork,
> + struct realtek_pci_sdmmc, rw_idle_work);
> + struct mmc_command *cmd;
> +
> + cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
> +
> + cmd->opcode = MMC_STOP_TRANSMISSION;
> + cmd->arg = 0;
> + cmd->busy_timeout = 0;
> + if (host->cur_dir == DMA_DIR_FROM_CARD)
> + cmd->flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
> + else
> + cmd->flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
> +
> + sd_send_cmd_get_rsp(host, cmd);
> + host->rw_mode = NORMAL_RW;
> + kfree(cmd);
> +}
> +
> +static int sd_check_multi_seq(struct realtek_pci_sdmmc *host, struct mmc_request *mrq)
> +{
> + struct mmc_command *cmd = mrq->cmd;
> + struct mmc_data *data = mrq->data;
> +
> + if (!mmc_op_multi(cmd->opcode))
> + return 0;
> +
> + if (host->prev_dir != host->cur_dir)
> + return 0;
> +
> + if ((host->prev_sec_addr + host->prev_sec_cnt) != data->blk_addr)
> + return 0;
> +
> + return 1;
> +}
> +
> static void sd_request(struct work_struct *work)
> {
> struct realtek_pci_sdmmc *host = container_of(work,
> @@ -841,12 +984,36 @@ static void sd_request(struct work_struct *work)
> if (!data_size) {
> sd_send_cmd_get_rsp(host, cmd);
> } else if (sd_rw_cmd(cmd) || sdio_extblock_cmd(cmd, data)) {
> - cmd->error = sd_rw_multi(host, mrq);
> - if (!host->using_cookie)
> - sdmmc_post_req(host->mmc, host->mrq, 0);
> + /* Check multi-block and seq function*/
> + if (data->flags & MMC_DATA_READ)
> + host->cur_dir = DMA_DIR_FROM_CARD;
> + else
> + host->cur_dir = DMA_DIR_TO_CARD;
> +
> + if (host->rw_mode == SEQ_RW) {
> + cancel_delayed_work(&host->rw_idle_work);
> + if (!sd_check_multi_seq(host, mrq)) {
> + sd_stop_rw_multi_seq(host, mrq);
> + host->rw_mode = NORMAL_RW;
> + }
> + }
> +
> + if (host->rw_mode == SEQ_RW)
> + cmd->error = sd_rw_multi_seq(host, mrq);
> + else {
> + if (mmc_op_multi(cmd->opcode))
> + host->rw_mode = SEQ_RW;
> + cmd->error = sd_rw_multi(host, mrq);
> + if (!host->using_cookie)
> + sdmmc_post_req(host->mmc, host->mrq, 0);
> + }
> +
> + if (cmd->error)
> + host->rw_mode = NORMAL_RW;
> +
> + if (mmc_op_multi(cmd->opcode) && host->rw_mode == SEQ_RW)
> + mod_delayed_work(system_wq, &host->rw_idle_work, msecs_to_jiffies(150));
>
> - if (mmc_op_multi(cmd->opcode) && mrq->stop)
> - sd_send_cmd_get_rsp(host, mrq->stop);
> } else {
> sd_normal_rw(host, mrq);
> }
> @@ -867,6 +1034,11 @@ static void sd_request(struct work_struct *work)
> }
>
> mutex_lock(&host->host_mutex);
> + if (sd_rw_cmd(cmd) || sdio_extblock_cmd(cmd, data)) {
> + host->prev_dir = host->cur_dir;
> + host->prev_sec_addr = data->blk_addr;
> + host->prev_sec_cnt = data->blocks;
> + }
> host->mrq = NULL;
> mutex_unlock(&host->host_mutex);
>
> @@ -1457,6 +1629,7 @@ static void rtsx_pci_sdmmc_card_event(struct platform_device *pdev)
> struct realtek_pci_sdmmc *host = platform_get_drvdata(pdev);
>
> host->cookie = -1;
> + host->rw_mode = NORMAL_RW;
> mmc_detect_change(host->mmc, 0);
> }
>
> @@ -1487,6 +1660,7 @@ static int rtsx_pci_sdmmc_drv_probe(struct platform_device *pdev)
> host->cookie = -1;
> host->power_state = SDMMC_POWER_OFF;
> INIT_WORK(&host->work, sd_request);
> + INIT_DELAYED_WORK(&host->rw_idle_work, sd_rw_idle_work);
> platform_set_drvdata(pdev, host);
> pcr->slots[RTSX_SD_CARD].p_dev = pdev;
> pcr->slots[RTSX_SD_CARD].card_event = rtsx_pci_sdmmc_card_event;
> @@ -1526,6 +1700,7 @@ static int rtsx_pci_sdmmc_drv_remove(struct platform_device *pdev)
> pm_runtime_disable(&pdev->dev);
> }
>
> + cancel_delayed_work_sync(&host->rw_idle_work);
> cancel_work_sync(&host->work);
>
> mutex_lock(&host->host_mutex);
> --
> 2.25.1
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