From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Menon Subject: Re: [PATCH] mmc: omap_hsmmc: Add support for Erratum 2.1.1.128 in device tree boot Date: Wed, 5 Feb 2014 08:12:28 -0600 Message-ID: <52F246CC.6070600@ti.com> References: <1390260542-22213-1-git-send-email-nm@ti.com> <52F0E098.3050404@ti.com> <52F104B7.6040606@ti.com> <52F2465A.6060804@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52F2465A.6060804@ti.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Balaji T K Cc: devicetree@vger.kernel.org, Tony Lindgren , linux-mmc@vger.kernel.org, Chris Ball , linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: devicetree@vger.kernel.org On Wed 05 Feb 2014 08:10:34 AM CST, Balaji T K wrote: > On Tuesday 04 February 2014 08:48 PM, Nishanth Menon wrote: >> On 02/04/2014 06:44 AM, Balaji T K wrote: >>> On Tuesday 21 January 2014 04:59 AM, Nishanth Menon wrote: >>>> When device is booted using devicetree, platforms impacted by >>>> Erratum 2.1.1.128 is not detected easily in the mmc driver. This erratum >>>> indicates that the module cannot do multi-block transfers. >>>> >>>> Handle this by providing a boolean flag to indicate to driver that it is >>>> working on a hardware with mentioned limitation. >>>> >>>> Signed-off-by: Nishanth Menon >>>> --- >>>> >>>> This explains the logs I see: >>>> OMAP3430 LDP (ES2.2): >>>> uImage only boot: http://slexy.org/raw/s2YrbMAi7c >>>> uImage+dtb concatenated boot: http://slexy.org/raw/s20qVg17T0 >>>> >>>> With the following flag set, device is now able to consistently boot with >>>> device tree supported uImage+dtb concat boot. >>>> >>>> .../devicetree/bindings/mmc/ti-omap-hsmmc.txt | 2 ++ >>>> drivers/mmc/host/omap_hsmmc.c | 3 +++ >>>> 2 files changed, 5 insertions(+) >>>> >>>> diff --git a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt >>>> index 8c8908a..ab36f8b 100644 >>>> --- a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt >>>> +++ b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt >>>> @@ -26,6 +26,8 @@ specifier is required. >>>> dma-names: List of DMA request names. These strings correspond >>>> 1:1 with the DMA specifiers listed in dmas. The string naming is >>>> to be "rx" and "tx" for RX and TX DMA requests, respectively. >>>> +ti,erratum-2.1.1.128: boolean, for OMAP3430/OMAP35xx platforms with broken >>>> +multiblock reads >>> >>> Rather than ti,errata.. specific property, something like >>> caps no/disable multiblock read is more readable in my opinion, Otherwise >> >> Is'nt the better definition to state i have quirk X and allow the >> driver to do the necessary thing/things needed to handle quirk X? in >> this case, there is just one thing to do: broken multi_block_read, in >> the case of other quirks, there might be more than 1 thing to do.. let >> driver figure that out, dts just states the h/w capabilty or in this >> case, the quirk capability. >> > > But in this case there is only one. disable multi block read is more readable > than the errata reference, No strong feelings though. Considering this might set an precedence for other quirk description, I'd like to leave it as it stands. -- Regards, Nishanth Menon