From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christophe RICARD Subject: Re: [tpmdd-devel] [PATCH 13/16] tpm/tpm_i2c_stm_st33: Add tpm_lock mutex for safe irq management Date: Wed, 08 Oct 2014 07:21:22 +0200 Message-ID: <5434C9D2.7080003@gmail.com> References: <1412712189-1234-1-git-send-email-christophe-h.ricard@st.com> <1412712189-1234-14-git-send-email-christophe-h.ricard@st.com> <20141007215630.GB2366@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141007215630.GB2366-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe Cc: peterhuewe-Mmb7MZpHnFY@public.gmane.org, ashley-fm2HMyfA2y6tG0bUXCXiUA@public.gmane.org, tpmdd-yWjUBOtONefk1uMJSBkQmQ@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, christophe-h.ricard-qxv4g6HH51o@public.gmane.org, jean-luc.blanc-qxv4g6HH51o@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Jason, Here i want to prevent a TPM TIS write command sent when a TPM TIS read command is on going on the bus. Basically: - a TPM TIS write looks like the following format: - a TPM TIS read looks like the following format: If an interrupt occur a TPM TIS read might be interrupted by a TPM TIS write to clear the pending interrupt giving potentially something like that: The TPM behavior in this situation is unknown... Best Regards Christophe On 07/10/2014 23:56, Jason Gunthorpe wrote: > On Tue, Oct 07, 2014 at 10:03:06PM +0200, Christophe Ricard wrote: >> Adding tpm_lock mutex in order to guarantee that a i2c_read_data or a >> i2c_write_data will not get interrupted by a threaded interrupt. > Can you elaborate on this? > > Any call from the TPM core itself through 'ops' is locked already, and > I don't see this driver's IRQ handler doing I2C ops.. > > What scenario is this protecting against? > > Jason -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html