lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 13 May 2014 09:29:04 +0200 From: Linus Walleij <linus.walleij@...aro.org> To: Srinivas Kandagatla <srinivas.kandagatla@...aro.org> Cc: Russell King <linux@....linux.org.uk>, "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>, Chris Ball <chris@...ntf.net>, Ulf Hansson <ulf.hansson@...aro.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, agross@...cinc.com, "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org> Subject: Re: [PATCH v1 06/11] mmc: mmci: Qcomm: Add 3 clock cycle delay after register write On Tue, Apr 29, 2014 at 10:20 AM, <srinivas.kandagatla@...aro.org> wrote: > From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org> > > Most of the Qcomm SD card controller registers must be updated to the MCLK > domain so subsequent writes to registers will be ignored until 3 clock cycles > have passed. > > This patch adds a 3 clock cycle delay required after writing to controller > registers on Qualcomm SOCs. Without this delay all the register writes are not > successfull, resulting in not detecting cards. > > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org> Sounds like someone decided to clock the internal state machine in the MMCI using MCLK instead of PCLK :-( A bit nasty if this ends up in the fastpath (irq) though. Which it invariably does, right? > + /* > + * On QCom SD card controller, registers must be updated to the > + * MCLK domain so subsequent writes to this register will be ignored > + * for 3 clk cycles. > + */ > + if (host->hw_designer == AMBA_VENDOR_QCOM) > + udelay(1 + ((3 * USEC_PER_SEC)/host->mclk)); Add a new field in vendor data instead, and use DIV_ROUND_UP(): static struct variant_data variant_qcom = { .mclk_delayed_writes = true, (...) if (host->vendor->mclk_delayed_writes) udelay(DIV_ROUND_UP((3 * USEC_PER_SEC), host->mclk)); You get the idea. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists