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From: Bjorn Helgaas <helgaas@kernel.org>
To: "liuqi (BA)" <liuqi115@huawei.com>
Cc: "Krzysztof Wilczyński" <kw@linux.com>,
	Linuxarm <linuxarm@huawei.com>,
	will@kernel.org, mark.rutland@arm.com, bhelgaas@google.com,
	linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, zhangshaokun@hisilicon.com
Subject: Re: [PATCH v6 2/2] drivers/perf: hisi: Add driver for HiSilicon PCIe PMU
Date: Wed, 16 Jun 2021 10:23:43 -0500	[thread overview]
Message-ID: <20210616152343.GA2977964@bjorn-Precision-5520> (raw)
In-Reply-To: <d2524d34-648a-8667-dde9-3686bd4fd096@huawei.com>

On Wed, Jun 16, 2021 at 09:09:40AM +0800, liuqi (BA) wrote:
> On 2021/6/12 7:33, Krzysztof Wilczyński wrote:

> > > +static ssize_t hisi_pcie_event_sysfs_show(struct device *dev,
> > > +				   struct device_attribute *attr, char *buf)
> > > +{
> > > +	struct dev_ext_attribute *eattr;
> > > +
> > > +	eattr = container_of(attr, struct dev_ext_attribute, attr);
> > > +
> > > +	return sysfs_emit(buf, "config=0x%lx\n", (unsigned long)eattr->var);
> > > +}
> > 
> > I am not that familiar with the perf drivers, thus I might be completely
> > wrong here, but usually for sysfs objects a single value is preferred,
> > so that this "config=" technically would not be needed, unless this is
> > somewhat essential to the consumers of this attribute to know what the
> > value is?  What do you think?
>
> "config=" is a supported for userspace tool, it is a kind of alias, so
> cannot be remover here, thanks.

I don't understand this part.  This is brand-new functionality for the
kernel, so there's no requirement to maintain compatibility for
existing userspace tools.

If there's a similar sysfs show function for other perf drivers, and
you need to be compatible with *that*, fine.  But if this is merely
about being compatible with userspace that uses out-of-tree kernel
functionality, that's not a real factor.

Bjorn

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  reply	other threads:[~2021-06-16 15:25 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-31 13:32 [PATCH v6 0/2] drivers/perf: hisi: Add support for " Qi Liu
2021-05-31 13:32 ` [PATCH v6 1/2] docs: perf: Add description for HiSilicon PCIe PMU driver Qi Liu
2021-05-31 13:32 ` [PATCH v6 2/2] drivers/perf: hisi: Add driver for HiSilicon PCIe PMU Qi Liu
2021-06-11 16:23   ` Will Deacon
2021-06-14  9:20     ` Jonathan Cameron
2021-06-15  9:26       ` Will Deacon
2021-06-15  8:57     ` liuqi (BA)
2021-06-15  9:35       ` Will Deacon
2021-06-16  1:54         ` liuqi (BA)
2021-06-16 13:42           ` Will Deacon
2021-06-17 11:00             ` liuqi (BA)
2021-06-17 17:57               ` Will Deacon
2021-06-18  9:32                 ` liuqi (BA)
2021-06-21 17:59                   ` Will Deacon
2021-06-23  9:59                     ` liuqi (BA)
2021-06-11 23:33   ` Krzysztof Wilczyński
2021-06-16  1:09     ` liuqi (BA)
2021-06-16 15:23       ` Bjorn Helgaas [this message]
2021-06-16 17:27         ` Will Deacon
2021-06-16 14:14     ` Bjorn Helgaas
2021-06-11 10:04 ` [PATCH v6 0/2] drivers/perf: hisi: Add support for " liuqi (BA)

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