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From: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
To: Rob Herring <robh@kernel.org>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>,
	"linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
	BMC-SW <BMC-SW@aspeedtech.com>,
	"sboyd@kernel.org" <sboyd@kernel.org>,
	Steven Lee <steven_lee@aspeedtech.com>,
	"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"adrian.hunter@intel.com" <adrian.hunter@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"andrew@aj.id.au" <andrew@aj.id.au>,
	"mturquette@baylibre.com" <mturquette@baylibre.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH 10/10] dt-bindings: mmc: aspeed: Add a new compatible string
Date: Wed, 29 Sep 2021 03:03:43 +0000	[thread overview]
Message-ID: <HK0PR06MB278642C55052360B039853FAB2A99@HK0PR06MB2786.apcprd06.prod.outlook.com> (raw)
In-Reply-To: <CAL_Jsq+TZFXrvfJTjofVcnT6jJat-3SvWj+jAq0QST8ndfeUMA@mail.gmail.com>

Hi Rob

> -----Original Message-----
> From: Rob Herring <robh@kernel.org>
> Sent: Wednesday, September 29, 2021 6:28 AM
> To: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
> Subject: Re: [PATCH 10/10] dt-bindings: mmc: aspeed: Add a new compatible
> string
> 
> On Mon, Sep 27, 2021 at 9:51 PM Chin-Ting Kuo
> <chin-ting_kuo@aspeedtech.com> wrote:
> >
> > Hi Rob,
> >
> > > -----Original Message-----
> > > From: Rob Herring <robh@kernel.org>
> > > Sent: Tuesday, September 28, 2021 2:59 AM
> > > To: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
> > > Subject: Re: [PATCH 10/10] dt-bindings: mmc: aspeed: Add a new
> > > compatible string
> > >
> > > On Wed, Sep 22, 2021 at 06:31:16PM +0800, Chin-Ting Kuo wrote:
> > > > Add "aspeed,ast2600-emmc" compatible string for the sake of
> > > > distinguishing between SD and eMMC device.
> > >
> > > Why?
> > >
> > > Is the h/w block different? We already have properties to handle
> > > some of the eMMC specifics. Also, you can have a child node for the
> > > eMMC device if you need that.
> >
> > There are two SD/SDIO controllers in a AST2600 SoC.
> > One is for SD card and the other is for eMMC.
> > Although both of them are embedded in the same SoC, the design of
> > delay cell and the manufacture process are different. The delay phase
> > is definitely different and, thus, we need a flag, compatible, to distinguish the
> device, SD or eMMC.
> >
> > Without "aspeed,ast2600-emmc" compatible, of course, eMMC device can
> > work with original sdhci driver and device tree setting. But, for
> > ultra-speed or HS200 case, AST2600 SoC needs some phase delay which
> (maximum) value is different between SD and eMMC device.
> 
> This is quite common as tweaking the timing is also need per board.
> Look at what other bindings have done. A property is more appropriate here.

Okay, I will try to check whether there is an existing binding which can achieve this purpose.
Or, maybe, as you said, a property is better since this phase delay is a proprietary
HW design and is different between each chipset version.

> 
> Rob

Chin-Ting

      reply	other threads:[~2021-09-29  3:05 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 10:31 [PATCH 00/10] ASPEED SD/eMMC controller clock configuration Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 01/10] clk: aspeed: ast2600: Porting sdhci clock source Chin-Ting Kuo
2021-09-23  0:02   ` Joel Stanley
2021-09-23  5:31     ` Chin-Ting Kuo
2021-10-26  6:10   ` Paul Menzel
2021-11-26  2:27     ` Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 02/10] sdhci: aspeed: Add SDR50 support Chin-Ting Kuo
2021-10-26  0:31   ` Andrew Jeffery
2021-11-06 10:01     ` Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 03/10] dts: aspeed: ast2600: Support SDR50 for SD device Chin-Ting Kuo
2021-10-26  0:42   ` Andrew Jeffery
2021-11-06 10:01     ` Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 04/10] mmc: Add invert flag for clock phase signedness Chin-Ting Kuo
2021-10-26  0:52   ` Andrew Jeffery
2021-11-06 10:02     ` Chin-Ting Kuo
2021-11-08  0:21       ` Andrew Jeffery
2021-09-22 10:31 ` [PATCH 05/10] mmc: aspeed: Adjust delay taps calculation method Chin-Ting Kuo
2021-10-26  3:10   ` Andrew Jeffery
2021-11-06 10:05     ` Chin-Ting Kuo
2021-11-07 23:42       ` Andrew Jeffery
2021-09-22 10:31 ` [PATCH 06/10] arm: dts: aspeed: Change eMMC device compatible Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 07/10] arm: dts: aspeed: Adjust clock phase parameter Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 08/10] arm: dts: ibm: " Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 09/10] dt-bindings: mmc: aspeed: Add max-tap-delay property Chin-Ting Kuo
2021-09-27 18:40   ` Rob Herring
2021-09-28  2:50     ` Chin-Ting Kuo
2021-09-22 10:31 ` [PATCH 10/10] dt-bindings: mmc: aspeed: Add a new compatible string Chin-Ting Kuo
2021-09-27 18:59   ` Rob Herring
2021-09-28  2:50     ` Chin-Ting Kuo
2021-09-28 22:28       ` Rob Herring
2021-09-29  3:03         ` Chin-Ting Kuo [this message]

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