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Fri, 10 Jul 2026 12:02:44 -0700 (PDT) X-Received: by 2002:a05:6a20:9f8c:b0:3c0:9c19:659c with SMTP id adf61e73a8af0-3c110b7ba39mr273287637.68.1783710163656; Fri, 10 Jul 2026 12:02:43 -0700 (PDT) Received: from localhost ([50.35.46.84]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13b659d8da9sm78063641c88.14.2026.07.10.12.02.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Jul 2026 12:02:43 -0700 (PDT) Date: Fri, 10 Jul 2026 12:02:39 -0700 From: Jonathan Cameron To: Andre Przywara Cc: Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Len Brown , James Morse , Ben Horgan , Reinette Chatre , Fenghua Yu , Jonathan Cameron , Srivathsa L Rao , Ganapatrao Kulkarni , Trilok Soni , Srinivas Ramana , Niyas Sait , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 09/16] arm_mpam: let low level MSC write accessors return an error Message-ID: <20260710120239.00002f99@oss.qualcomm.com> In-Reply-To: <20260710144520.917375-10-andre.przywara@arm.com> References: <20260710144520.917375-1-andre.przywara@arm.com> <20260710144520.917375-10-andre.przywara@arm.com> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=Ab2B2XXG c=1 sm=1 tr=0 ts=6a5141d6 cx=c_pps a=oF/VQ+ItUULfLr/lQ2/icg==:117 a=qC1CW/w66vtJz1P9yTJxNA==:17 a=kj9zAlcOel0A:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=7CQSdrXTAAAA:8 a=LvQbmhgH5lkxUdBqBIQA:9 a=CjuIK1q_8ugA:10 a=3WC7DwWrALyhR5TkjVHa:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-ORIG-GUID: IfyY1hVZmwInJI0w-r3kTSBr2RPrR8o7 X-Proofpoint-GUID: IfyY1hVZmwInJI0w-r3kTSBr2RPrR8o7 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzEwMDE5MCBTYWx0ZWRfX8Td3SxLX+yOC DGcPcy7MOXUI9zfrn46o4LC3Tj5rsNffOOUWJNwRc+Z3oSaTMgr3wqZq/wd8bzjPnAD7Vox44S4 V2i0C7sJAcRuNhrJKqxF/fuKsSO9VDI= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzEwMDE5MCBTYWx0ZWRfXzkc9YYMpFQC6 zMvd6cMqS1T7OVKFgakjxnwFKNCTmxZD09xHf5pUv+BF0vy18ef/9k6UDZSRtn3U7DNDNO9cEdG VSnMOOjmG5HqYo1oMdwZ0p0SpGBtceJSnDS0sItAp1pbEc2BJUgdxWsx4R9WA95C1oTTFdCqTTS iJ4pofNKNY2C4IUdpesAi8gFS7a89t5vOtvCYsXFwVbAE9PoCwtOuHxbgj/iNMDJ4L4ZCb1IVZ9 le1yKsnIghkPhsachgVl7SxrVJFuMiJjTjZ8qT4ljmY0H9hukt8l7R7PGVh7Y9iA3w4aseEvmln CT86btjsQJnct3b6bKTcQZmGB6S+dUn/dpi/op6MZnPWWt7d6SyU2VqDnEsN2z66dSWkSNh39RP pfF4jQMfqoMCCbzQgTSkXrtqV78nimsKlk4U1RW+NMmUV0AG6OAQ/A5d9+jDdtKE5NcLuWwJv7b NEiMMgOHmUlOzMrQOLA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-10_05,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 malwarescore=0 phishscore=0 bulkscore=0 suspectscore=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607100190 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260710_120247_761489_B9AB4E0A X-CRM114-Status: GOOD ( 23.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 10 Jul 2026 16:45:13 +0200 Andre Przywara wrote: > The upcoming MPAM-Fb support does not use MMIO primitives to access an > MSC, but employs a shared-memory/doorbell based firmware protocol. > Its complexity means that is must be able to handle errors, whereas we > always assume an MSC access succeeds today. > > Change the __mpam_write_reg() low level accessor function to return an > error code. At the moment this is always 0, but this will change with > alternative MSC access methods. > > Also change some low level wrappers to propagate the error. > > Signed-off-by: Andre Przywara I mentioned earlier that to me a split of read vs write into different series of patches is making things more complex than they might be. They are same 'sort' of change so I'd do them together. Then a reviewer can quickly see if all new sources of error are covered. Thanks (and sorry I didn't look at v2!) Jonathan > --- > drivers/resctrl/mpam_devices.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index b2ecaba29fcc..f1e40ce24f5a 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -195,18 +195,20 @@ static inline int _mpam_read_partsel_reg(struct mpam_msc *msc, u16 reg, > > #define mpam_read_partsel_reg(msc, reg, res) _mpam_read_partsel_reg(msc, MPAMF_##reg, res) > > -static void __mpam_write_reg(struct mpam_msc *msc, u16 reg, u32 val) > +static int __mpam_write_reg(struct mpam_msc *msc, u16 reg, u32 val) > { > WARN_ON_ONCE(reg + sizeof(u32) > msc->mapped_hwpage_sz); > WARN_ON_ONCE(!cpumask_test_cpu(smp_processor_id(), &msc->accessibility)); > > writel_relaxed(val, msc->mapped_hwpage + reg); > + > + return 0; > } > > -static inline void _mpam_write_partsel_reg(struct mpam_msc *msc, u16 reg, u32 val) > +static inline int _mpam_write_partsel_reg(struct mpam_msc *msc, u16 reg, u32 val) > { > lockdep_assert_held_once(&msc->part_sel_lock); > - __mpam_write_reg(msc, reg, val); > + return __mpam_write_reg(msc, reg, val); > } > > #define mpam_write_partsel_reg(msc, reg, val) _mpam_write_partsel_reg(msc, MPAMCFG_##reg, val) > @@ -220,10 +222,10 @@ static inline int _mpam_read_monsel_reg(struct mpam_msc *msc, u16 reg, > > #define mpam_read_monsel_reg(msc, reg, res) _mpam_read_monsel_reg(msc, MSMON_##reg, res) > > -static inline void _mpam_write_monsel_reg(struct mpam_msc *msc, u16 reg, u32 val) > +static inline int _mpam_write_monsel_reg(struct mpam_msc *msc, u16 reg, u32 val) > { > mpam_mon_sel_lock_held(msc); > - __mpam_write_reg(msc, reg, val); > + return __mpam_write_reg(msc, reg, val); > } > > #define mpam_write_monsel_reg(msc, reg, val) _mpam_write_monsel_reg(msc, MSMON_##reg, val)