Re: [v2,3/3] mmc: mediatek: add optional module reset property

[Greg KH]

On Wed, Aug 12, 2020 at 09:01:29PM +0800, Wenbin Mei wrote:
> This patch fixs eMMC-Access on mt7622/Bpi-64.
> Before we got these Errors on mounting eMMC ion R64:
> [   48.664925] blk_update_request: I/O error, dev mmcblk0, sector 204800 op 0x1:(WRITE)
> flags 0x800 phys_seg 1 prio class 0
> [   48.676019] Buffer I/O error on dev mmcblk0p1, logical block 0, lost sync page write
> 
> This patch adds a optional reset management for msdc.
> Sometimes the bootloader does not bring msdc register
> to default state, so need reset the msdc controller.
> 
> Fixes: 966580ad236e ("mmc: mediatek: add support for MT7622 SoC")
> Signed-off-by: Wenbin Mei <wenbin.mei@xxxxxxxxxxxx>
> Tested-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
> ---
>  drivers/mmc/host/mtk-sd.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 39e7fc54c438..2b243c03c9b2 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -22,6 +22,7 @@
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <linux/interrupt.h>
> +#include <linux/reset.h>
>  
>  #include <linux/mmc/card.h>
>  #include <linux/mmc/core.h>
> @@ -434,6 +435,7 @@ struct msdc_host {
>  	struct msdc_save_para save_para; /* used when gate HCLK */
>  	struct msdc_tune_para def_tune_para; /* default tune setting */
>  	struct msdc_tune_para saved_tune_para; /* tune result of CMD21/CMD19 */
> +	struct reset_control *reset;
>  };
>  
>  static const struct mtk_mmc_compatible mt8135_compat = {
> @@ -1516,6 +1518,12 @@ static void msdc_init_hw(struct msdc_host *host)
>  	u32 val;
>  	u32 tune_reg = host->dev_comp->pad_tune_reg;
>  
> +	if (!IS_ERR(host->reset)) {
> +		reset_control_assert(host->reset);
> +		usleep_range(10, 50);
> +		reset_control_deassert(host->reset);
> +	}
> +
>  	/* Configure to MMC/SD mode, clock free running */
>  	sdr_set_bits(host->base + MSDC_CFG, MSDC_CFG_MODE | MSDC_CFG_CKPDN);
>  
> @@ -2273,6 +2281,11 @@ static int msdc_drv_probe(struct platform_device *pdev)
>  	if (IS_ERR(host->src_clk_cg))
>  		host->src_clk_cg = NULL;
>  
> +	host->reset = devm_reset_control_get_optional_exclusive(&pdev->dev,
> +								"hrst");
> +	if (PTR_ERR(host->reset) == -EPROBE_DEFER)
> +		return PTR_ERR(host->reset);
> +
>  	host->irq = platform_get_irq(pdev, 0);
>  	if (host->irq < 0) {
>  		ret = -EINVAL;
> -- 
> 2.18.0

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>