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SubjectRe: [PATCH v4 2/2] mmc: dw_mmc: add reset support to dwmmc host controller
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On 2016/8/10 16:03, Guodong Xu wrote:
> Dwmmc host controller may in unknown state when entering kernel boot. One
> example is when booting from eMMC, bootloader need initialize MMC host
> controller into some state so it can read. In order to make sure MMC host
> controller in a clean initial state, this reset support is added.
>
> With this patch, a 'resets' property can be added into dw_mmc device
> tree node. The hardware logic is: dwmmc host controller IP receives a reset
> signal from a 'reset provider' (eg. power management unit). The 'resets'
> property points to this reset signal. So, during dwmmc driver probe,
> it can use this signal to reset itself.
>
> Refer to [1] for more information.
>
> [1] Documentation/devicetree/bindings/reset/reset.txt
>
> Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
> Signed-off-by: Xinwei Kong <kong.kongxinwei@hisilicon.com>
> Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>

Looks good to me,

Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>

> ---
> drivers/mmc/host/dw_mmc.c | 23 ++++++++++++++++++++++-
> include/linux/mmc/dw_mmc.h | 2 ++
> 2 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 32380d5..481d441 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -2915,6 +2915,13 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
> if (!pdata)
> return ERR_PTR(-ENOMEM);
>
> + /* find reset controller when exist */
> + pdata->rstc = devm_reset_control_get_optional(dev, NULL);
> + if (IS_ERR(pdata->rstc)) {
> + if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER)
> + return ERR_PTR(-EPROBE_DEFER);
> + }
> +
> /* find out number of slots supported */
> of_property_read_u32(np, "num-slots", &pdata->num_slots);
>
> @@ -2986,7 +2993,9 @@ int dw_mci_probe(struct dw_mci *host)
>
> if (!host->pdata) {
> host->pdata = dw_mci_parse_dt(host);
> - if (IS_ERR(host->pdata)) {
> + if (PTR_ERR(host->pdata) == -EPROBE_DEFER) {
> + return -EPROBE_DEFER;
> + } else if (IS_ERR(host->pdata)) {
> dev_err(host->dev, "platform data not available\n");
> return -EINVAL;
> }
> @@ -3040,6 +3049,12 @@ int dw_mci_probe(struct dw_mci *host)
> }
> }
>
> + if (!IS_ERR(host->pdata->rstc)) {
> + reset_control_assert(host->pdata->rstc);
> + usleep_range(10, 50);
> + reset_control_deassert(host->pdata->rstc);
> + }
> +
> setup_timer(&host->cmd11_timer,
> dw_mci_cmd11_timer, (unsigned long)host);
>
> @@ -3189,6 +3204,9 @@ err_dmaunmap:
> if (host->use_dma && host->dma_ops->exit)
> host->dma_ops->exit(host);
>
> + if (!IS_ERR(host->pdata->rstc))
> + reset_control_assert(host->pdata->rstc);
> +
> err_clk_ciu:
> if (!IS_ERR(host->ciu_clk))
> clk_disable_unprepare(host->ciu_clk);
> @@ -3221,6 +3239,9 @@ void dw_mci_remove(struct dw_mci *host)
> if (host->use_dma && host->dma_ops->exit)
> host->dma_ops->exit(host);
>
> + if (!IS_ERR(host->pdata->rstc))
> + reset_control_assert(host->pdata->rstc);
> +
> if (!IS_ERR(host->ciu_clk))
> clk_disable_unprepare(host->ciu_clk);
>
> diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
> index 83b0edfc..f5af2bd 100644
> --- a/include/linux/mmc/dw_mmc.h
> +++ b/include/linux/mmc/dw_mmc.h
> @@ -17,6 +17,7 @@
> #include <linux/scatterlist.h>
> #include <linux/mmc/core.h>
> #include <linux/dmaengine.h>
> +#include <linux/reset.h>
>
> #define MAX_MCI_SLOTS 2
>
> @@ -259,6 +260,7 @@ struct dw_mci_board {
> /* delay in mS before detecting cards after interrupt */
> u32 detect_delay_ms;
>
> + struct reset_control *rstc;
> struct dw_mci_dma_ops *dma_ops;
> struct dma_pdata *data;
> };
>


--
Best Regards
Shawn Lin

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