From: Florian Fainelli <f.fainelli@gmail.com>
To: David Daney <ddaney@caviumnetworks.com>,
Andrew Lunn <andrew@lunn.ch>,
David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org,
James Hogan <james.hogan@mips.com>,
netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org,
"Steven J. Hill" <steven.hill@cavium.com>,
devicetree@vger.kernel.org, Carlos Munoz <cmunoz@cavium.com>
Subject: Re: [PATCH 3/7] MIPS: Octeon: Add a global resource manager.
Date: Thu, 2 Nov 2017 10:49:19 -0700 [thread overview]
Message-ID: <6ff04462-88ec-a972-4084-e26ea3cb630a@gmail.com> (raw)
In-Reply-To: <caeae680-915a-d08c-d220-899db0970328@caviumnetworks.com>
On 11/02/2017 09:03 AM, David Daney wrote:
> On 11/02/2017 05:23 AM, Andrew Lunn wrote:
>>> +static void res_mgr_lock(void)
>>> +{
>>> + unsigned int tmp;
>>> + u64 lock = (u64)&res_mgr_info->rlock;
>>> +
>>> + __asm__ __volatile__(
>>> + ".set noreorder\n"
>>> + "1: ll %[tmp], 0(%[addr])\n"
>>> + " bnez %[tmp], 1b\n"
>>> + " li %[tmp], 1\n"
>>> + " sc %[tmp], 0(%[addr])\n"
>>> + " beqz %[tmp], 1b\n"
>>> + " nop\n"
>>> + ".set reorder\n" :
>>> + [tmp] "=&r"(tmp) :
>>> + [addr] "r"(lock) :
>>> + "memory");
>>> +}
>>> +
>>> +static void res_mgr_unlock(void)
>>> +{
>>> + u64 lock = (u64)&res_mgr_info->rlock;
>>> +
>>> + /* Wait until all resource operations finish before unlocking. */
>>> + mb();
>>> + __asm__ __volatile__(
>>> + "sw $0, 0(%[addr])\n" : :
>>> + [addr] "r"(lock) :
>>> + "memory");
>>> +
>>> + /* Force a write buffer flush. */
>>> + mb();
>>> +}
>>
>> It would be good to add some justification for using your own locks,
>> rather than standard linux locks.
>
> Yes, I will add that.
>
>
>>
>> Is there anything specific to your hardware in this resource manager?
>> I'm just wondering if this should be generic, put somewhere in lib. Or
>> maybe there is already something generic, and you should be using it,
>> not re-inventing the wheel again.
>
> The systems built around this hardware may have other software running
> on CPUs that are not running the Linux kernel. The data structures used
> to arbitrate usage of shared system hardware resources use exactly these
> locking primitives, so they cannot be changed to use the Linux locking
> implementation de jour.
Would hwspinlock be a possible option so this is abstracted on the Linux
side using these locking primitives through the hwspinlock layer which
in turn does exactly what is above?
--
Florian
next prev parent reply other threads:[~2017-11-02 17:49 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-02 0:35 [PATCH 0/7] Cavium OCTEON-III network driver David Daney
2017-11-02 0:36 ` [PATCH 1/7] dt-bindings: Add Cavium Octeon Common Ethernet Interface David Daney
2017-11-02 1:09 ` Florian Fainelli
2017-11-02 1:26 ` David Daney
2017-11-02 12:47 ` Andrew Lunn
2017-11-02 16:06 ` David Daney
2017-11-02 0:36 ` [PATCH 2/7] MIPS: Octeon: Enable LMTDMA/LMTST operations David Daney
2017-11-02 0:36 ` [PATCH 3/7] MIPS: Octeon: Add a global resource manager David Daney
2017-11-02 12:23 ` Andrew Lunn
2017-11-02 16:03 ` David Daney
2017-11-02 17:49 ` Florian Fainelli [this message]
2017-11-02 0:36 ` [PATCH 4/7] MIPS: Octeon: Add Free Pointer Unit (FPA) support David Daney
2017-11-02 3:29 ` Florian Fainelli
2017-11-02 16:27 ` David Daney
2017-11-02 18:04 ` Florian Fainelli
2017-11-02 19:12 ` David Daney
2017-11-02 13:14 ` James Hogan
2017-11-02 0:36 ` [PATCH 5/7] MIPS: Octeon: Automatically provision CVMSEG space David Daney
2017-11-05 7:45 ` kbuild test robot
2017-11-02 0:36 ` [PATCH 6/7] netdev: octeon-ethernet: Add Cavium Octeon III support David Daney
2017-11-02 12:43 ` Andrew Lunn
2017-11-02 15:55 ` David Daney
2017-11-02 16:10 ` Andrew Lunn
2017-11-02 16:37 ` David Daney
2017-11-02 16:56 ` Andrew Lunn
2017-11-02 18:31 ` David Daney
2017-11-02 18:53 ` Florian Fainelli
2017-11-02 19:13 ` Florian Fainelli
2017-11-02 22:45 ` David Daney
2017-11-03 15:48 ` Andrew Lunn
2017-11-02 0:36 ` [PATCH 7/7] MAINTAINERS: Add entry for drivers/net/ethernet/cavium/octeon/octeon3-* David Daney
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