From: Olof Johansson <olof@lixom.net>
To: Andy Gross <andy.gross@linaro.org>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Kevin Hilman <khilman@baylibre.com>,
Russell King <linux@armlinux.org.uk>
Subject: Re: [Patch v4 2/2] firmware: qcom: scm: Fix interrupted SCM calls
Date: Sun, 29 Jan 2017 16:24:51 -0800 [thread overview]
Message-ID: <CAOesGMi4xUxJNHO5hEbZHBCnTZ6xXVyzoszawPiJxBiRP1DitA@mail.gmail.com> (raw)
In-Reply-To: <1484845120-3364-3-git-send-email-andy.gross@linaro.org>
Hi,
On Thu, Jan 19, 2017 at 8:58 AM, Andy Gross <andy.gross@linaro.org> wrote:
> This patch adds a Qualcomm specific quirk to the arm_smccc_smc call.
>
> On Qualcomm ARM64 platforms, the SMC call can return before it has
> completed. If this occurs, the call can be restarted, but it requires
> using the returned session ID value from the interrupted SMC call.
>
> The quirk stores off the session ID from the interrupted call in the
> quirk structure so that it can be used by the caller.
>
> This patch folds in a fix given by Sricharan R:
> https://lkml.org/lkml/2016/9/28/272
>
> Signed-off-by: Andy Gross <andy.gross@linaro.org>
> Reviewed-by: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/kernel/smccc-call.S | 9 ++++++++-
> drivers/firmware/qcom_scm-64.c | 13 ++++++++++---
> include/linux/arm-smccc.h | 11 ++++++++---
> 3 files changed, 26 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kernel/smccc-call.S b/arch/arm64/kernel/smccc-call.S
> index 6290696..72ecdca 100644
> --- a/arch/arm64/kernel/smccc-call.S
> +++ b/arch/arm64/kernel/smccc-call.S
> @@ -12,6 +12,7 @@
> *
> */
> #include <linux/linkage.h>
> +#include <linux/arm-smccc.h>
> #include <asm/asm-offsets.h>
>
> .macro SMCCC instr
> @@ -20,7 +21,13 @@
> ldr x4, [sp]
> stp x0, x1, [x4, #ARM_SMCCC_RES_X0_OFFS]
> stp x2, x3, [x4, #ARM_SMCCC_RES_X2_OFFS]
> - ret
> + ldr x4, [sp, #8]
> + cbz x4, 1f /* no quirk structure */
> + ldr x9, [x4, #ARM_SMCCC_QUIRK_ID_OFFS]
> + cmp x9, #ARM_SMCCC_QUIRK_QCOM_A6
> + b.ne 1f
> + str x6, [x4, ARM_SMCCC_QUIRK_STATE_OFFS]
> +1: ret
> .cfi_endproc
> .endm
This extends the SMC entry/return path quite a bit.
Is this truly a qualcomm-only quirk, or are other vendors also picking it up?
Why not either make arm_smccc_.* function pointers and update them
accordingly, or use a custom version for the specific locations where
you want/need to restart the calls? You are after all already wrapping
them in qcom_scm_call().
Seems like a more appropriate change than burden all platforms with
longer code path due to your quirk.
-Olof
next prev parent reply other threads:[~2017-01-30 1:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-19 16:58 [Patch v4 0/2] Support ARM SMCC SoC vendor quirks Andy Gross
2017-01-19 16:58 ` [Patch v4 1/2] arm: kernel: Add SMC structure parameter Andy Gross
2017-01-19 16:58 ` [Patch v4 2/2] firmware: qcom: scm: Fix interrupted SCM calls Andy Gross
2017-01-30 0:24 ` Olof Johansson [this message]
2017-01-30 10:55 ` Will Deacon
2017-01-31 6:22 ` Olof Johansson
2017-01-31 14:45 ` Will Deacon
2017-01-31 16:03 ` Andy Gross
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