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From:   Rahul Tanwar <rtanwar@maxlinear.com>
To:     Stephen Boyd <sboyd@kernel.org>,
        "linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>,
        "mturquette@baylibre.com" <mturquette@baylibre.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-lgm-soc <linux-lgm-soc@maxlinear.com>,
        Yi xin Zhu <yzhu@maxlinear.com>
Subject: Re: [PATCH RESEND v2 2/5] clk: mxl: Remove unnecessary spinlocks
Thread-Topic: [PATCH RESEND v2 2/5] clk: mxl: Remove unnecessary spinlocks
Thread-Index: AQHYzkwE27uHBIRl/k+jM2EqBGGnfg==
Date:   Thu, 29 Sep 2022 05:37:12 +0000
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On 29/9/2022 8:16 am, Stephen Boyd wrote:=0A> This email was sent from outs=
ide of MaxLinear.=0A>=20=0A>=20=0A> Quoting Rahul Tanwar (2022-09-21 23:24:=
25)=0A>> This driver is now switched from direct readl/writel based registe=
r=0A>> access to regmap based register acceess. Regmap already has its own=
=0A>> lock to serialize the register accesses across multiple cores.=0A>>=
=0A>> Hence, there is no need for additional spinlocks in the driver.=0A>> =
Remove all spinlocks which are no longer required.=0A>=20=0A> Can you confi=
rm that the driver doesn't do a read, modify, write (rmw)=0A> sequence wher=
e during the modification another CPU can rmw and corrupt=0A> the previous =
"read"?=0A=0A=0AFor rmw, driver uses regmap_update_bits() API. All regmap A=
PI's use=20=0Atheir own spinlocks before doing any read or write or rmw.=0A=
=0APatch 1/5 switches from direct readl/writel to regmap based API's for=0A=
register read/write/rmw in which case additional driver spinlock becomes=0A=
redundant. So this patch 2/5 removes redundant driver spin locks.=0A=0AThan=
ks,=0ARahul=0A=0A=0A>=20=0A>=20=0A=0A