linux-kernel - Re: [PATCH] mmc: rtsx_pci: add quirk to disable MMC_CAP_AGGRESSIVE

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Message-ID: <db872779-c1a5-4d93-9143-61a8f29b27a6@linux.dev>
Date: Sun, 4 Jan 2026 16:46:47 -0800
From: Matthew Schwartz <matthew.schwartz@...ux.dev>
To: Ulf Hansson <ulf.hansson@...aro.org>, Arnd Bergmann <arnd@...db.de>,
 Ricky Wu <ricky_wu@...ltek.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: rtsx_pci: add quirk to disable MMC_CAP_AGGRESSIVE_PM
 for RTS525A

On 1/3/26 12:42 PM, Matthew Schwartz wrote:
> Using MMC_CAP_AGGRESSIVE_PM on RTS525A card readers causes game
> performance issues when the card reader comes back from idle into active
> use. This can be observed in Hades II when loading new sections of the
> game or menu after the card reader puts itself into idle, and presents
> as a 1-2 second hang.
> 
> Add EXTRA_CAPS_NO_AGGRESSIVE_PM quirk to allow cardreader drivers to
> opt-out of aggressive PM, and set it for RTS525A.

Bit of an update: I dug up an old laptop that has a Realtek RTS5261 PCI card reader, and that has the exact same issue under identical circumstances.
It might make more sense to skip the quirking and just make no MMC_CAP_AGGRESSIVE_PM the default in rtsx_pci_sdmmc unless another solution can be found.

Matt

> 
> Closes: https://lore.kernel.org/linux-mmc/ff9a7c20-f465-4afa-bf29-708d4a52974a@linux.dev/
> Signed-off-by: Matthew Schwartz <matthew.schwartz@...ux.dev>
> ---
>  drivers/misc/cardreader/rts5249.c | 3 +++
>  drivers/mmc/host/rtsx_pci_sdmmc.c | 4 ++--
>  include/linux/rtsx_pci.h          | 1 +
>  3 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/cardreader/rts5249.c b/drivers/misc/cardreader/rts5249.c
> index 38aefd8db452..87d576a03e68 100644
> --- a/drivers/misc/cardreader/rts5249.c
> +++ b/drivers/misc/cardreader/rts5249.c
> @@ -78,6 +78,9 @@ static void rtsx_base_fetch_vendor_settings(struct rtsx_pcr *pcr)
>  	if (CHK_PCI_PID(pcr, PID_524A) || CHK_PCI_PID(pcr, PID_525A))
>  		pcr->rtd3_en = rtsx_reg_to_rtd3_uhsii(reg);
>  
> +	if (CHK_PCI_PID(pcr, PID_525A))
> +		pcr->extra_caps |= EXTRA_CAPS_NO_AGGRESSIVE_PM;
> +
>  	if (rtsx_check_mmc_support(reg))
>  		pcr->extra_caps |= EXTRA_CAPS_NO_MMC;
>  	pcr->sd30_drive_sel_3v3 = rtsx_reg_to_sd30_drive_sel_3v3(reg);
> diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
> index dc2587ff8519..5d3599ee06bf 100644
> --- a/drivers/mmc/host/rtsx_pci_sdmmc.c
> +++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
> @@ -1456,8 +1456,8 @@ static void realtek_init_host(struct realtek_pci_sdmmc *host)
>  	mmc->caps = MMC_CAP_4_BIT_DATA | MMC_CAP_SD_HIGHSPEED |
>  		MMC_CAP_MMC_HIGHSPEED | MMC_CAP_BUS_WIDTH_TEST |
>  		MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
> -	if (pcr->rtd3_en)
> -		mmc->caps = mmc->caps | MMC_CAP_AGGRESSIVE_PM;
> +	if (pcr->rtd3_en && !(pcr->extra_caps & EXTRA_CAPS_NO_AGGRESSIVE_PM))
> +		mmc->caps |= MMC_CAP_AGGRESSIVE_PM;
>  	mmc->caps2 = MMC_CAP2_NO_PRESCAN_POWERUP | MMC_CAP2_FULL_PWR_CYCLE |
>  		MMC_CAP2_NO_SDIO;
>  	mmc->max_current_330 = 400;
> diff --git a/include/linux/rtsx_pci.h b/include/linux/rtsx_pci.h
> index 3c5689356004..f6122349c00e 100644
> --- a/include/linux/rtsx_pci.h
> +++ b/include/linux/rtsx_pci.h
> @@ -1230,6 +1230,7 @@ struct rtsx_pcr {
>  #define EXTRA_CAPS_MMC_8BIT		(1 << 5)
>  #define EXTRA_CAPS_NO_MMC		(1 << 7)
>  #define EXTRA_CAPS_SD_EXPRESS		(1 << 8)
> +#define EXTRA_CAPS_NO_AGGRESSIVE_PM	(1 << 9)
>  	u32				extra_caps;
>  
>  #define IC_VER_A			0