Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > linux.kernel > #1499882 > unrolled thread

[RFC v2 1/2] sdhci: Add device tree property broken-highspeed

Started byZach Brown <zach.brown@ni.com>
First post2016-10-12 20:50 +0200
Last post2016-10-18 15:20 +0200
Articles 3 — 3 participants

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.


Contents

  [RFC v2 1/2] sdhci: Add device tree property broken-highspeed Zach Brown <zach.brown@ni.com> - 2016-10-12 20:50 +0200
    Re: [RFC v2 1/2] sdhci: Add device tree property broken-highspeed Jaehoon Chung <jh80.chung@samsung.com> - 2016-10-13 04:30 +0200
    Re: [RFC v2 1/2] sdhci: Add device tree property broken-highspeed Rob Herring <robh@kernel.org> - 2016-10-18 15:20 +0200

#1499882 — [RFC v2 1/2] sdhci: Add device tree property broken-highspeed

FromZach Brown <zach.brown@ni.com>
Date2016-10-12 20:50 +0200
Subject[RFC v2 1/2] sdhci: Add device tree property broken-highspeed
Message-ID<srwLf-8fi-5@gated-at.bofh.it>
Certain board configurations can make highspeed malfuction due to timing
issues. In these cases a way is needed to force the controller and card
into standard speed even if they otherwise appear to be capable of
highspeed.

The broken-highspeed property will let the sdhci driver know that
highspeed will not work.

Signed-off-by: Zach Brown <zach.brown@ni.com>
---
 Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index 8a37782..a2b298c 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -52,6 +52,8 @@ Optional properties:
 - no-sdio: controller is limited to send sdio cmd during initialization
 - no-sd: controller is limited to send sd cmd during initialization
 - no-mmc: controller is limited to send mmc cmd during initialization
+- broken-highspeed: Highspeed is broken, even if the controller and card
+  themselves claim they support highspeed.
 
 *NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line
 polarity properties, we have to fix the meaning of the "normal" and "inverted"
-- 
2.7.4

[toc] | [next] | [standalone]


#1500000

FromJaehoon Chung <jh80.chung@samsung.com>
Date2016-10-13 04:30 +0200
Message-ID<srDWq-5iJ-9@gated-at.bofh.it>
In reply to#1499882
On 10/13/2016 03:40 AM, Zach Brown wrote:
> Certain board configurations can make highspeed malfuction due to timing
> issues. In these cases a way is needed to force the controller and card
> into standard speed even if they otherwise appear to be capable of
> highspeed.

I'm not sure "broken-hishspeed" property is relevant to only sdhci driver? otherwise on card side..?
Subject looks like only sdhci driver..And your RFC patch should be supported only SDHCI driver.
But your [patch 1/2] can cause the confusing in future..because there are just comment as "controller".

Then developer who refer to mmc.txt will add the property "broken-highspeed".
I'm not sure what is correct way..but to prevent confusing..you mentioned only "sdhci" driver or supporting other controller.

Best Regards,
Jaehoon Chung

> 
> The broken-highspeed property will let the sdhci driver know that
> highspeed will not work.
> 
> Signed-off-by: Zach Brown <zach.brown@ni.com>
> ---
>  Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
> index 8a37782..a2b298c 100644
> --- a/Documentation/devicetree/bindings/mmc/mmc.txt
> +++ b/Documentation/devicetree/bindings/mmc/mmc.txt
> @@ -52,6 +52,8 @@ Optional properties:
>  - no-sdio: controller is limited to send sdio cmd during initialization
>  - no-sd: controller is limited to send sd cmd during initialization
>  - no-mmc: controller is limited to send mmc cmd during initialization
> +- broken-highspeed: Highspeed is broken, even if the controller and card
> +  themselves claim they support highspeed.
>  
>  *NOTE* on CD and WP polarity. To use common for all SD/MMC host controllers line
>  polarity properties, we have to fix the meaning of the "normal" and "inverted"
> 

[toc] | [prev] | [next] | [standalone]


#1502986

FromRob Herring <robh@kernel.org>
Date2016-10-18 15:20 +0200
Message-ID<stCtb-294-11@gated-at.bofh.it>
In reply to#1499882
On Wed, Oct 12, 2016 at 01:40:55PM -0500, Zach Brown wrote:
> Certain board configurations can make highspeed malfuction due to timing
> issues. In these cases a way is needed to force the controller and card
> into standard speed even if they otherwise appear to be capable of
> highspeed.
> 
> The broken-highspeed property will let the sdhci driver know that
> highspeed will not work.
> 
> Signed-off-by: Zach Brown <zach.brown@ni.com>
> ---
>  Documentation/devicetree/bindings/mmc/mmc.txt | 2 ++
>  1 file changed, 2 insertions(+)

Acked-by: Rob Herring <robh@kernel.org>

[toc] | [prev] | [standalone]


Back to top | Article view | linux.kernel


csiph-web