On Fri, Apr 27 2018 at 12:40 -0600, Matthias Kaehlcke wrote:
On Fri, Apr 27, 2018 at 11:39:43AM -0600, Lina Iyer wrote:On Wed, Apr 25 2018 at 15:41 -0600, Matthias Kaehlcke wrote: > On Thu, Apr 19, 2018 at 04:16:30PM -0600, Lina Iyer wrote: > > Sleep and wake requests are sent when the application processor > > subsystem of the SoC is entering deep sleep states like in suspend. > > These requests help lower the system power requirements when the > > resources are not in use. > > > > Sleep and wake requests are written to the TCS slots but are not > > triggered at the time of writing. The TCS are triggered by the firmware > > after the last of the CPUs has executed its WFI. Since these requests > > may come in different batches of requests, it is the job of this > > controller driver to find and arrange the requests into the available > > TCSes. > > > > Signed-off-by: Lina Iyer <ilina@xxxxxxxxxxxxxx> > > Reviewed-by: Evan Green <evgreen@xxxxxxxxxxxx> > > --- > > drivers/soc/qcom/rpmh-internal.h | 8 +++ > > drivers/soc/qcom/rpmh-rsc.c | 120 +++++++++++++++++++++++++++++++ > > 2 files changed, 128 insertions(+) > > > > diff --git a/drivers/soc/qcom/rpmh-internal.h b/drivers/soc/qcom/rpmh-internal.h > > index d9a21726e568..6e19fe458c31 100644 > > --- a/drivers/soc/qcom/rpmh-internal.h > > +++ b/drivers/soc/qcom/rpmh-internal.h > > <snip> > > > +static int find_match(const struct tcs_group *tcs, const struct tcs_cmd *cmd, > > + int len) > > +{ > > + int i, j; > > + > > + /* Check for already cached commands */ > > + for_each_set_bit(i, tcs->slots, MAX_TCS_SLOTS) { > > + for (j = 0; j < len; j++) { > > + if (tcs->cmd_cache[i] != cmd[0].addr) { > > Shouldn't the condition be 'tcs->cmd_cache[i + j] != cmd[j].addr'? > Here, we are trying to find the first address from the request and its position 'i' in the cmd_cache. > Otherwise the code below the following if branch will never be > executed. Either the 'tcs->cmd_cache[i] != cmd[0].addr' branch isn't > entered because the addresses match, or the addresses don't match > and the inner loop is aborted after the first iteration. > > > + if (j == 0) > > + break; > > + WARN(tcs->cmd_cache[i + j] != cmd[j].addr, > > + "Message does not match previous sequence.\n"); We now check for the sequence using the iterator 'j' only after we have found 'i' (the beginning of our request). I hope that helps clear the concern.It doesn't, maybe I'm just confused, the driver has a certain complexity and I don't claim to have a comprehensive understanding :) If I understand correctly find_match() is used to find a sequence of commands of length 'len' in the command cache. If that is correct I would expect it to do the following: 1. iterate through the commands in the command cache and find a command that matches the first command in the sequence 2. verify that the (len - 1) subsequent commands match those in the sequence, otherwise bail out If I'm not mistaken the current version of find_match() only checks that the first command exists. After that it happily increases the command index, but doesn't perform any checks (after finding the first command 'tcs->cmd_cache[i] != cmd[0].addr' remains false for the subsequent values of j). When j reaches (len - 1) the function returns the index of the first command in the cache, regardless of whether the other commands match or not.
Did you miss the check inside the WARN? WARN(tcs->cmd_cache[i + j] != cmd[j].addr, --Lina -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
