From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kymetacorp.com ([192.81.58.21]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Zx2MV-0004BO-H8 for barebox@lists.infradead.org; Fri, 13 Nov 2015 00:37:08 +0000 From: Trent Piepho Date: Fri, 13 Nov 2015 00:36:22 +0000 Message-ID: <1447374984.4553.133.camel@rtred1test09.kymeta.local> Content-Language: en-US Content-ID: MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: MCI bus-width host caps via device tree don't work properly for dw and imx To: barebox I found my 4-bit connected eMMC chip wasn't working because barebox was trying to run it in 8-bit mode. I had the proper bus-width property in the device tree, but this doesn't work. The problem is that mci_of_parse() uses bus-width to _add_ 8-bit and/or 4-bit caps to the host. It doesn't remove any host_caps the driver already has set. So if the driver supports 8-bit but the DT bus-width is 4, you still get a driver that thinks 8-bit will work. You can see this in dw_mmc.c, dw_mmc_probe() sets: host->mci.host_caps = MMC_CAP_4_BIT_DATA | MMC_CAP_8_BIT_DATA then later mci_of_parse(&host->mci); return mci_register(&host->mci); The mci_of_parse call will not remove the 4 and 8 bits caps. There is the same problem in imx-esdhc.c. The other two users of mci_of_parse, mxs.c and tegra-sdmmc.c, don't have this problem, since they don't set any bus-width host_caps in the driver and depend on the DT or platform_data to have this info. With drivers split 50/50, which is the right way? Don't have the driver report what bits it supports and depend on the device tree to have that information? Or have of_mci_parse remove widths that aren't indicated as supported in the DT, so that the DT can remove widths the hardware indicates it supports. _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox