Re: [PATCH V7 4/5] mmc: sdhci: Add support for O2 hardware tuning

[Adrian Hunter]

On 16/07/18 09:26, ernest.zhang wrote:
> Add hardware tuning function instead of software tuning because O2/Bayhub
> SD host controller support hardware tuning.
> 
> Signed-off-by: ernest.zhang <ernest.zhang@xxxxxxxxxxxxxx>

Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>


> ---
> Changes in V7:
> 	Move V6 change item 1 to a seperate patch.
> 
> Changes in V6:
> 	1. From module 'sdhci' export the symbols 'sdhci_start_tuning',
> 	'sdhci_end_tuning','sdhci_send_tuning' and 'sdhci_reset_tuning'.
> 	2. Remove local tuning related functions in sdhci-pci-o2-micro.c
> 	instead of above function exported in sdhci module.
> 	3. Remove unneeded braces in function sdhci_set_transfer_mode.
> 	4. Move change log to correct place.
> 
> Changes in V5:
> 	In function sdhci_o2_send_tuning, mrq.data should set to NULL for
> 	cmd.data has been set to NULL.
> 
> Changes in V4:
> 	Patch V3 delete register SDHCI_TRANSFER_MODE write operation before
> 	send hardware tuning command in function sdhci_o2_send_tuning. This
> 	is a mistake. The write operation is essential for tuning command.
> 	Add it back.
> 
> Changes in V3:
> 	Rebase the patch on the mmc tree 'next' branch.
> 
> Changes in V2:
> 	Modify code format, and delete unused code path.
> 
> Changes in V1:
> 	Add many functions to execute hardware tuning for eMMC 1.8V HS200
> 	mode, the hardware tuning procedure is based on O2/Bayhub hardware
> 	tuning spec.
> ---
>  drivers/mmc/host/sdhci-pci-o2micro.c | 81 ++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci.c             |  4 +-
>  2 files changed, 84 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c
> index 94cf3cd75dd3..7747e8ba2e3d 100644
> --- a/drivers/mmc/host/sdhci-pci-o2micro.c
> +++ b/drivers/mmc/host/sdhci-pci-o2micro.c
> @@ -17,6 +17,9 @@
>   */
>  
>  #include <linux/pci.h>
> +#include <linux/mmc/host.h>
> +#include <linux/mmc/mmc.h>
> +#include <linux/delay.h>
>  
>  #include "sdhci.h"
>  #include "sdhci-pci.h"
> @@ -55,6 +58,82 @@
>  
>  #define O2_SD_VENDOR_SETTING	0x110
>  #define O2_SD_VENDOR_SETTING2	0x1C8
> +#define O2_SD_HW_TUNING_DISABLE	BIT(4)
> +
> +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_DISABLE;
> +	sdhci_writew(host, reg, O2_SD_VENDOR_SETTING);
> +}
> +
> +static void __sdhci_o2_execute_tuning(struct sdhci_host *host, u32 opcode)
> +{
> +	int i;
> +
> +	sdhci_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_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_start_tuning(host);
> +
> +	__sdhci_o2_execute_tuning(host, opcode);
> +
> +	sdhci_end_tuning(host);
> +
> +	if (current_bus_width == MMC_BUS_WIDTH_8)
> +		sdhci_set_bus_width(host, current_bus_width);
> +
> +	host->flags &= ~SDHCI_HS400_TUNING;
> +	return 0;
> +}
>  
>  static void o2_pci_set_baseclk(struct sdhci_pci_chip *chip, u32 value)
>  {
> @@ -215,6 +294,8 @@ 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;
>  		/* set dll watch dog timer */
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index bcea179a8d70..1b3fbd9bd5c5 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1029,7 +1029,9 @@ 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);
>