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Message-ID: <2A308283684ECD4B896628E09AF5361E028BCA26@RS-MBS01.realsil.com.cn>
Date: Mon, 27 Apr 2020 09:40:48 +0000
From: 冯锐 <rui_feng@...lsil.com.cn>
To: Christoph Hellwig <hch@...radead.org>
CC: "arnd@...db.de" <arnd@...db.de>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: 答复: [PATCH] mmc: rtsx: Add SD Express mode support for RTS5261
> On Sun, Apr 26, 2020 at 09:25:46AM +0800, rui_feng@...lsil.com.cn wrote:
> > From: Rui Feng <rui_feng@...lsil.com.cn>
> >
> > RTS5261 support legacy SD mode and SD Express mode.
> > In SD7.x, SD association introduce SD Express as a new mode.
> > SD Express mode is distinguished by CMD8.
> > Therefore, CMD8 has new bit for SD Express.
> > SD Express is based on PCIe/NVMe.
> > RTS5261 uses CMD8 to switch to SD Express mode.
>
> So how does this bit work? They way I imagined SD Express to work is that
> the actual SD Card just shows up as a real PCIe device, similar to say
> Thunderbolt.
New SD Express card has dual mode. One is SD mode and another is PCIe mode.
In PCIe mode, it act as a PCIe device and use PCIe protocol not Thunderbolt protocol.
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