From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [RESEND][PATCH] tpm: read burstcount from TPM_STS in one 32-bit transaction Date: Fri, 1 Jul 2016 11:45:45 +0300 Message-ID: <20160701084545.GA16059@intel.com> References: <1467307543-44566-1-git-send-email-apronin@chromium.org> <20160701084323.GA15718@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20160701084323.GA15718-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: apronin-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org Cc: Christophe Ricard , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net On Fri, Jul 01, 2016 at 11:43:23AM +0300, Jarkko Sakkinen wrote: > On Thu, Jun 30, 2016 at 10:25:43AM -0700, apronin-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org wrote: > > From: Andrey Pronin > > > > Some chips incorrectly support partial reads from TPM_STS register > > at non-zero offsets. Read the entire 32-bits register instead of > > making two 8-bit reads to support such devices and reduce the number > > of bus transactions when obtaining the burstcount from TPM_STS. > > > > Signed-off-by: Andrey Pronin > > Reviewed-by: Jarkko Sakkinen Applied to my master branch. /Jarkko > > /Jarkko > > > --- > > > > No changes. > > Re-sending to tpmdd-devel member-only list after subscribing. > > > > drivers/char/tpm/tpm_tis_core.c | 11 +++-------- > > 1 file changed, 3 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > > index 03a06b3..8110b52 100644 > > --- a/drivers/char/tpm/tpm_tis_core.c > > +++ b/drivers/char/tpm/tpm_tis_core.c > > @@ -157,22 +157,17 @@ static int get_burstcount(struct tpm_chip *chip) > > struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); > > unsigned long stop; > > int burstcnt, rc; > > - u8 value; > > + u32 value; > > > > /* wait for burstcount */ > > /* which timeout value, spec has 2 answers (c & d) */ > > stop = jiffies + chip->timeout_d; > > do { > > - rc = tpm_tis_read8(priv, TPM_STS(priv->locality) + 1, &value); > > + rc = tpm_tis_read32(priv, TPM_STS(priv->locality), &value); > > if (rc < 0) > > return rc; > > > > - burstcnt = value; > > - rc = tpm_tis_read8(priv, TPM_STS(priv->locality) + 2, &value); > > - if (rc < 0) > > - return rc; > > - > > - burstcnt += value << 8; > > + burstcnt = (value >> 8) & 0xFFFF; > > if (burstcnt) > > return burstcnt; > > msleep(TPM_TIMEOUT); > > -- > > 2.6.6 > > ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape