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From: Kevin Hilman <khilman@baylibre.com>
To: Alexander Stein <alexander.stein@mailbox.org>,
	Rob Herring <robh+dt@kernel.org>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Neil Armstrong <narmstrong@baylibre.com>
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-amlogic@lists.infradead.org
Subject: Re: [PATCH 1/1] arm64: dts: meson: g12b: odroid-n2: Assign a fixed index to mmc devices
Date: Mon, 01 Feb 2021 16:50:35 -0800	[thread overview]
Message-ID: <7hv9bbgun8.fsf@baylibre.com> (raw)
In-Reply-To: <1975982.ltkoRUPMKj@kongar>

Alexander Stein <alexander.stein@mailbox.org> writes:

> Hi,
>
> Am Freitag, 29. Januar 2021, 09:07:45 CET schrieb Neil Armstrong:
>> On 28/01/2021 00:08, Alexander Stein wrote:
>> > Recently introduced async probe on mmc devices can shuffle block IDs.
>> > Pin them to fixed values to ease booting in environments where UUIDs
>> > are not practical. Use newly introduced aliases for mmcblk devices from 
> [1].
>> > [1]
>> > https://patchwork.kernel.org/patch/11747669/
>> 
>> I understand the goal, and this should be done for _all_ boards, not only 
> the Odroid-N2.
>
> I see. So there are 2 options:
> 1.
> Set the mapping for all 3 sd_emmc_* in the top-most .dtsi
> Upside: very easy patch
> Downside: When sd_emmc_a is not enabled "mmc0" will never be available.
> Might be confusing.

sd_emmc_a is (almost?) always the iface used for SDIO devices, which are
not always present.

I would recommend we go with a single mapping in the top-level .dtsi

  SD card -> mmc0  (sd_emmc_b)
  eMMC    -> mmc1  (sd_emmc_c)
  SDIO    -> mmc2  (sd_emmc_a)

it's not exactly obvious why we don't go 0,1,2 == A,B,C but just
document it in the top-level .dtsi.

This approach also has the benefit of having the devices show up how
many/most boards showed up before the async probe changes.

Kevin

_______________________________________________
linux-amlogic mailing list
linux-amlogic@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic

WARNING: multiple messages have this Message-ID (diff)
From: Kevin Hilman <khilman@baylibre.com>
To: Alexander Stein <alexander.stein@mailbox.org>,
	Rob Herring <robh+dt@kernel.org>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Neil Armstrong <narmstrong@baylibre.com>
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-amlogic@lists.infradead.org
Subject: Re: [PATCH 1/1] arm64: dts: meson: g12b: odroid-n2: Assign a fixed index to mmc devices
Date: Mon, 01 Feb 2021 16:50:35 -0800	[thread overview]
Message-ID: <7hv9bbgun8.fsf@baylibre.com> (raw)
In-Reply-To: <1975982.ltkoRUPMKj@kongar>

Alexander Stein <alexander.stein@mailbox.org> writes:

> Hi,
>
> Am Freitag, 29. Januar 2021, 09:07:45 CET schrieb Neil Armstrong:
>> On 28/01/2021 00:08, Alexander Stein wrote:
>> > Recently introduced async probe on mmc devices can shuffle block IDs.
>> > Pin them to fixed values to ease booting in environments where UUIDs
>> > are not practical. Use newly introduced aliases for mmcblk devices from 
> [1].
>> > [1]
>> > https://patchwork.kernel.org/patch/11747669/
>> 
>> I understand the goal, and this should be done for _all_ boards, not only 
> the Odroid-N2.
>
> I see. So there are 2 options:
> 1.
> Set the mapping for all 3 sd_emmc_* in the top-most .dtsi
> Upside: very easy patch
> Downside: When sd_emmc_a is not enabled "mmc0" will never be available.
> Might be confusing.

sd_emmc_a is (almost?) always the iface used for SDIO devices, which are
not always present.

I would recommend we go with a single mapping in the top-level .dtsi

  SD card -> mmc0  (sd_emmc_b)
  eMMC    -> mmc1  (sd_emmc_c)
  SDIO    -> mmc2  (sd_emmc_a)

it's not exactly obvious why we don't go 0,1,2 == A,B,C but just
document it in the top-level .dtsi.

This approach also has the benefit of having the devices show up how
many/most boards showed up before the async probe changes.

Kevin

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Kevin Hilman <khilman@baylibre.com>
To: Alexander Stein <alexander.stein@mailbox.org>,
	Rob Herring <robh+dt@kernel.org>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Neil Armstrong <narmstrong@baylibre.com>
Cc: devicetree@vger.kernel.org, linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] arm64: dts: meson: g12b: odroid-n2: Assign a fixed index to mmc devices
Date: Mon, 01 Feb 2021 16:50:35 -0800	[thread overview]
Message-ID: <7hv9bbgun8.fsf@baylibre.com> (raw)
In-Reply-To: <1975982.ltkoRUPMKj@kongar>

Alexander Stein <alexander.stein@mailbox.org> writes:

> Hi,
>
> Am Freitag, 29. Januar 2021, 09:07:45 CET schrieb Neil Armstrong:
>> On 28/01/2021 00:08, Alexander Stein wrote:
>> > Recently introduced async probe on mmc devices can shuffle block IDs.
>> > Pin them to fixed values to ease booting in environments where UUIDs
>> > are not practical. Use newly introduced aliases for mmcblk devices from 
> [1].
>> > [1]
>> > https://patchwork.kernel.org/patch/11747669/
>> 
>> I understand the goal, and this should be done for _all_ boards, not only 
> the Odroid-N2.
>
> I see. So there are 2 options:
> 1.
> Set the mapping for all 3 sd_emmc_* in the top-most .dtsi
> Upside: very easy patch
> Downside: When sd_emmc_a is not enabled "mmc0" will never be available.
> Might be confusing.

sd_emmc_a is (almost?) always the iface used for SDIO devices, which are
not always present.

I would recommend we go with a single mapping in the top-level .dtsi

  SD card -> mmc0  (sd_emmc_b)
  eMMC    -> mmc1  (sd_emmc_c)
  SDIO    -> mmc2  (sd_emmc_a)

it's not exactly obvious why we don't go 0,1,2 == A,B,C but just
document it in the top-level .dtsi.

This approach also has the benefit of having the devices show up how
many/most boards showed up before the async probe changes.

Kevin

  reply	other threads:[~2021-02-02  0:50 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-27 23:08 [PATCH 1/1] arm64: dts: meson: g12b: odroid-n2: Assign a fixed index to mmc devices Alexander Stein
2021-01-27 23:08 ` Alexander Stein
2021-01-27 23:08 ` Alexander Stein
2021-01-29  8:07 ` Neil Armstrong
2021-01-29  8:07   ` Neil Armstrong
2021-01-29 20:51   ` Alexander Stein
2021-01-29 20:51     ` Alexander Stein
2021-01-29 20:51     ` Alexander Stein
2021-02-02  0:50     ` Kevin Hilman [this message]
2021-02-02  0:50       ` Kevin Hilman
2021-02-02  0:50       ` Kevin Hilman
2021-02-02 17:03 ` [PATCH v2 1/1] arm64: dts: amlogic: " Alexander Stein
2021-02-02 17:03   ` Alexander Stein
2021-02-02 17:03   ` Alexander Stein
2021-02-03 19:20   ` Kevin Hilman
2021-02-03 19:20     ` Kevin Hilman
2021-02-03 19:20     ` Kevin Hilman
2021-02-03 19:28 ` [PATCH v3 " Alexander Stein
2021-02-03 19:28   ` Alexander Stein
2021-02-03 19:28   ` Alexander Stein
2021-02-18 18:09   ` Alexander Stein
2021-02-18 18:09     ` Alexander Stein
2021-02-18 18:09     ` Alexander Stein
2021-03-08 17:43     ` Kevin Hilman
2021-03-08 17:43       ` Kevin Hilman
2021-03-08 17:43       ` Kevin Hilman
2021-10-02  6:56       ` Alexander Stein
2021-10-02  6:56         ` Alexander Stein
2021-10-02  6:56         ` Alexander Stein
2021-10-02  8:49         ` Neil Armstrong
2021-10-02  8:49           ` Neil Armstrong
2021-10-02  8:49           ` Neil Armstrong
2021-10-02  8:54           ` Alexander Stein
2021-10-02  8:54             ` Alexander Stein
2021-10-02  8:54             ` Alexander Stein
2021-03-08 17:39   ` Kevin Hilman
2021-03-08 17:39     ` Kevin Hilman
2021-03-08 17:39     ` Kevin Hilman

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