linux-kernel - Re: [PATCH 0/2] Fix V1P8_SIGNAL_ENA and HIGH_SPEED

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Message-ID: <3f31eded-4a7b-43f0-819f-a3be48cffc7b@ti.com>
Date: Wed, 16 Apr 2025 11:59:16 -0500
From: Judith Mendez <jm@...com>
To: Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson
	<ulf.hansson@...aro.org>
CC: <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Josua Mayer
	<josua@...id-run.com>, Moteen Shah <m-shah@...com>,
        Hiago De Franco
	<hiago.franco@...adex.com>
Subject: Re: [PATCH 0/2] Fix V1P8_SIGNAL_ENA and HIGH_SPEED_ENA

Hello Adrian,

On 4/7/25 5:27 PM, Judith Mendez wrote:
> For all TI devices, timing was closed For Legacy and HS modes in
> half cycle timing, where data is launched on the negative edge of
> clock and latched on the following positive edge of clock. The
> switch to full cycle timing happens when any of HIGH_SPEED_ENA,
> V1P8_SIGNAL_ENA, or UHS_MODE_SELECT is set.
> 
> Currently HIGH_SPEED_ENA is set for HS modes and violates timing
> requirements for TI devices so add a .set_hs_ena callback in
> sdhci_am654 driver so that HIGH_SPEED_ENA is not set for this mode.
> 
> There are eMMC boot failures seen with V1P8_SIGNAL_ENA with a
> specific Kingston eMMC due to the sequencing when enumerating to
> HS200 mode. Since V1P8_SIGNAL_ENA is optional for eMMC, do not
> set V1P8_SIGNAL_ENA be default. This fix was previously merged in
> the kernel, but was reverted due to the "heuristics for enabling
> the quirk"[0]. The new implementation applies the quirk based-off of
> bus width, which should not be an issue since there is no internal
> LDO for MMC0 8bit wide interface and hence V1P8_SIGNAL_ENA should only
> effect timing for MMC0 interface.


On this patch series, I am bringing back the fix for V1P8_SIGNAL_ENA,
Ulf requested a change [0] which I am planning to do for v2. But I was
hoping to get your opinion on whether Hiago's suggestion [1] is doable
so I can add that as well to v2. Thanks for your attention.


[0] 
https://lore.kernel.org/linux-mmc/CAPDyKFqx-G4NynanFWrspz7-uXXF74RfjcU-Sw2nq2JhL3LPuQ@mail.gmail.com/
[1] 
https://lore.kernel.org/linux-mmc/20250412132012.xpjywokcpztb4jg4@hiago-nb/

~ Judith