On Wed, Aug 21, 2013 at 6:49 AM, Seungwon Jeon <tgih.jun@xxxxxxxxxxx> wrote:
> Implements variable delay tuning. In this change,
> exynos host can determine the correct sampling point
> for the HS200 and SDR104 speed mode.
>
> Signed-off-by: Seungwon Jeon <tgih.jun@xxxxxxxxxxx>
> ---
> drivers/mmc/host/dw_mmc-exynos.c | 124 ++++++++++++++++++++++++++++++++++++++
> 1 files changed, 124 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
> index 866edef..90f9335 100644
> --- a/drivers/mmc/host/dw_mmc-exynos.c
> +++ b/drivers/mmc/host/dw_mmc-exynos.c
> @@ -14,8 +14,10 @@
> #include <linux/clk.h>
> #include <linux/mmc/host.h>
> #include <linux/mmc/dw_mmc.h>
> +#include <linux/mmc/mmc.h>
> #include <linux/of.h>
> #include <linux/of_gpio.h>
> +#include <linux/slab.h>
>
> #include "dw_mmc.h"
> #include "dw_mmc-pltfm.h"
> @@ -150,6 +152,127 @@ static int dw_mci_exynos_parse_dt(struct dw_mci *host)
> return 0;
> }
>
> +static inline u8 dw_mci_exynos_get_clksmpl(struct dw_mci *host)
> +{
> + return SDMMC_CLKSEL_CCLK_SAMPLE(mci_readl(host, CLKSEL));
> +}
> +
> +static inline void dw_mci_exynos_set_clksmpl(struct dw_mci *host, u8 sample)
> +{
> + u32 clksel;
> + clksel = mci_readl(host, CLKSEL);
> + clksel = (clksel & ~0x7) | SDMMC_CLKSEL_CCLK_SAMPLE(sample);
> + mci_writel(host, CLKSEL, clksel);
> +}
> +
> +static inline u8 dw_mci_exynos_move_next_clksmpl(struct dw_mci *host)
Hi Seungwon,
I rewrote the dw_mmc HS200 tuning code for ChromeOS-3.4 kernel with
this series of patches:
https://gerrit.chromium.org/gerrit/#/c/57997 CHROMIUM: mmc:
dw_mmc: move struct dw_mci_slot to public header
https://gerrit.chromium.org/gerrit/#/c/58269 CHROMIUM: mmc:
dw_mmc: move dw_mci_set_timeout() to dw_mmc.h
https://gerrit.chromium.org/gerrit/#/c/57996/ CHROMIUM: mmc:
dw_mmc: add execute_tuning hook
https://gerrit.chromium.org/gerrit/#/c/57861 CHROMIUM: mmc:
dw_mmc: add HS200 tuning feature
This code was reviewed and approved by Alim Akhtar.
Most of the differences I don't care enough about to quibble. But the
handling of "clksmpl" was difficult to read and understand. I added a
lot of comments so the next person without access to Samsung's
confidential and incomplete Exynos manuals could have a small chance
of debugging this code.
In particular look at dw_mci_exynos_execute_tuning() and
find_median_of_5bits() in this patch:
https://gerrit.chromium.org/gerrit/#/c/57861/9/drivers/mmc/host/dw_mmc-exynos.c
Is there some reason you would NOT want to use find_median_of_5bits()
and related code?
thanks,
grant
> +{
> + u32 clksel;
> + u8 sample;
> +
> + clksel = mci_readl(host, CLKSEL);
> + sample = (clksel + 1) & 0x7;
> + clksel = (clksel & ~0x7) | sample;
> + mci_writel(host, CLKSEL, clksel);
> + return sample;
> +}
> +
> +static s8 dw_mci_exynos_get_best_clksmpl(u8 candiates)
> +{
> + const u8 iter = 8;
> + u8 __c;
> + s8 i, loc = -1;
> +
> + for (i = 0; i < iter; i++) {
> + __c = ror8(candiates, i);
> + if ((__c & 0xc7) == 0xc7) {
> + loc = i;
> + goto out;
> + }
> + }
> +
> + for (i = 0; i < iter; i++) {
> + __c = ror8(candiates, i);
> + if ((__c & 0x83) == 0x83) {
> + loc = i;
> + goto out;
> + }
> + }
> +
> +out:
> + return loc;
> +}
> +
> +static int dw_mci_exynos_execute_tuning(struct dw_mci_slot *slot, u32 opcode,
> + struct dw_mci_tuning_data *tuning_data)
> +{
> + struct dw_mci *host = slot->host;
> + struct mmc_host *mmc = slot->mmc;
> + const u8 *blk_pattern = tuning_data->blk_pattern;
> + u8 *blk_test;
> + unsigned int blksz = tuning_data->blksz;
> + u8 start_smpl, smpl, candiates = 0;
> + s8 found = -1;
> + int ret = 0;
> +
> + blk_test = kmalloc(blksz, GFP_KERNEL);
> + if (!blk_test)
> + return -ENOMEM;
> +
> + start_smpl = dw_mci_exynos_get_clksmpl(host);
> +
> + do {
> + struct mmc_request mrq = {NULL};
> + struct mmc_command cmd = {0};
> + struct mmc_command stop = {0};
> + struct mmc_data data = {0};
> + struct scatterlist sg;
> +
> + cmd.opcode = opcode;
> + cmd.arg = 0;
> + cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
> +
> + stop.opcode = MMC_STOP_TRANSMISSION;
> + stop.arg = 0;
> + stop.flags = MMC_RSP_R1B | MMC_CMD_AC;
> +
> + data.blksz = blksz;
> + data.blocks = 1;
> + data.flags = MMC_DATA_READ;
> + data.sg = &sg;
> + data.sg_len = 1;
> +
> + sg_init_one(&sg, blk_test, blksz);
> + mrq.cmd = &cmd;
> + mrq.stop = &stop;
> + mrq.data = &data;
> + host->mrq = &mrq;
> +
> + mci_writel(host, TMOUT, ~0);
> + smpl = dw_mci_exynos_move_next_clksmpl(host);
> +
> + mmc_wait_for_req(mmc, &mrq);
> +
> + if (!cmd.error && !data.error) {
> + if (!memcmp(blk_pattern, blk_test, blksz))
> + candiates |= (1 << smpl);
> + } else {
> + dev_dbg(host->dev,
> + "Tuning error: cmd.error:%d, data.error:%d\n",
> + cmd.error, data.error);
> + }
> + } while (start_smpl != smpl);
> +
> + found = dw_mci_exynos_get_best_clksmpl(candiates);
> + if (found >= 0)
> + dw_mci_exynos_set_clksmpl(host, found);
> + else
> + ret = -EIO;
> +
> + kfree(blk_test);
> + return ret;
> +}
> +
> /* Common capabilities of Exynos4/Exynos5 SoC */
> static unsigned long exynos_dwmmc_caps[4] = {
> MMC_CAP_UHS_DDR50 | MMC_CAP_1_8V_DDR |
> @@ -166,6 +289,7 @@ static const struct dw_mci_drv_data exynos_drv_data = {
> .prepare_command = dw_mci_exynos_prepare_command,
> .set_ios = dw_mci_exynos_set_ios,
> .parse_dt = dw_mci_exynos_parse_dt,
> + .execute_tuning = dw_mci_exynos_execute_tuning,
> };
>
> static const struct of_device_id dw_mci_exynos_match[] = {
> --
> 1.7.0.4
>
>
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