RE: [PATCH 2/2] mmc: renesas_sdhi: support manual calibration

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>
Cc: "linux-renesas-soc@vger.kernel.org" 
	<linux-renesas-soc@vger.kernel.org>,
	Takeshi Saito <takeshi.saito.xv@renesas.com>
Subject: RE: [PATCH 2/2] mmc: renesas_sdhi: support manual calibration
Date: Mon, 31 Aug 2020 06:22:55 +0000	[thread overview]
Message-ID: <TY2PR01MB369224E06BAE72C1711B681AD8510@TY2PR01MB3692.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <20200605101222.10783-3-wsa+renesas@sang-engineering.com>

Hi Wolfram-san,

Thank you for the patch!
 (And, I'm sorry for the delayed response.)

> From: Wolfram Sang, Sent: Friday, June 5, 2020 7:12 PM
> 
> Some R-Car Gen3 SoCs need some manual correction of timing parameters
> after the automatic tuning has finished but before next CMD13 is
> completed. This patch implements that by this state machine:
> 
> - introducing a per-SoC correction table if needed
> - iff such a table exists, the 'fixup_request' callback is populated
>   during probe
> - iff such a table exists, a runtime flag ('needs_adjust_hs400')
>   is set when HS400 tuning gets prepared

We should set the needs_adjust_hs400 when HS400EN=1 is set.
In other words, we should set it in renesas_sdhi_hs400_complete(),
not renesas_sdhi_prepare_hs400_tuning().

> - if tuning HS400 fails, the runtime flag is cleared again
> - the callback will check the runtime flag and enable the corrected
>   manual mode if the flag is set and CMD13 is encountered
> - at the end of the enablement the runtime flag is cleared
> - iff the configuration flag is set, the manual mode will be disabled
>   when HS400 gets downgraded
> 
> There also some helper functions added to access the TMPPORT registers.
> The actual correction table is SoC and instance(!) specific and is
> added to the quirks struct.
> 
> Signed-off-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
<snip>
> +static void renesas_sdhi_adjust_hs400_mode_enable(struct tmio_mmc_host *host)
> +{
> +	struct renesas_sdhi *priv = host_to_priv(host);
> +	u32 calib_code;
> +
> +	/* disable write protect */
> +	sd_scc_tmpport_write32(host, priv, 0x00,
> +			       SH_MOBILE_SDHI_SCC_TMPPORT_DISABLE_WP_CODE);
> +	/* read calibration code and adjust */
> +	calib_code = sd_scc_tmpport_read32(host, priv, 0x26);

When we read the calib_code at room temperature, the value will be around 0x10.
However, we will get 0x00 here. So, we need to fix it.

Best regards,
Yoshihiro Shimoda