From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [PATCH] mmc: fix incorrect interpretation of card type bits Date: Tue, 23 Mar 2010 07:52:58 +0200 Message-ID: <4BA8573A.5010302@nokia.com> References: <4BA318B8.5060408@nokia.com> <20100322154318.5fffc3bf.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.nokia.com ([192.100.122.233]:26011 "EHLO mgw-mx06.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751426Ab0CWFxF (ORCPT ); Tue, 23 Mar 2010 01:53:05 -0400 In-Reply-To: <20100322154318.5fffc3bf.akpm@linux-foundation.org> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Andrew Morton Cc: "linux-mmc@vger.kernel.org" Andrew Morton wrote: > On Fri, 19 Mar 2010 08:24:56 +0200 > Adrian Hunter wrote: > >> From: Adrian Hunter >> Date: Fri, 19 Mar 2010 08:06:54 +0200 >> Subject: [PATCH] mmc: fix incorrect interpretation of card type bits >> >> In the extended CSD register the CARD_TYPE is an 8-bit value >> of which the upper 6 bits were reserved in JEDEC specifications >> prior to version 4.4. In version 4.4 two of the reserved bits >> were designated for identifying support for the newly added >> High-Speed Dual Data Rate. Unfortunately the mmc_read_ext_csd() >> function required that the reserved bits be zero instead of >> ignoring them as it should. >> >> This patch makes mmc_read_ext_csd() ignore the CARD_TYPE bits >> that are reserved or not yet supported. It also stops the >> function jumping to the end as though an error occurred, when >> it is only warns that the CARD_TYPE bits (that it does interpret) >> are invalid. > > I need to whine about the changelog again. > > I'm guessing that the effect here is that if someone puts one of these > new cards into an old kernel, this card will be incorrectly handled. > Perhaps in ways which render the whole thing useless. This is for eMMC so that will not happen. > If that was a good guess then this patch would be needed in earlier > kernels too. > > But it was only a guess, and I'd prefer not to have to guess. So > please do remember to explain things like this in the changelog? OK. "Backport not necessary."