From mboxrd@z Thu Jan  1 00:00:00 1970
From: t-kristo@ti.com (Tero Kristo)
Date: Fri, 11 Dec 2015 10:43:35 +0200
Subject: [PATCH] clk: ti: omap5+: dpll: implement errata i810
In-Reply-To: <20151203164817.GT23396@atomide.com>
References: <1448894605-30097-1-git-send-email-t-kristo@ti.com>
 <20151203164817.GT23396@atomide.com>
Message-ID: <566A8CB7.4050701@ti.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 12/03/2015 06:48 PM, Tony Lindgren wrote:
> * Tero Kristo <t-kristo@ti.com> [151130 06:44]:
>> +	/*
>> +	 * Errata i810 - DPLL controller can get stuck while transitioning
>> +	 * to a power saving state. Software must ensure the DPLL can not
>> +	 * transition to a low power state while changing M/N values.
>> +	 * Easiest way to accomplish this is to prevent DPLL autoidle
>> +	 * before doing the M/N re-program.
>> +	 */
>> +	errata_i810 = ti_clk_get_features()->flags & TI_CLK_ERRATA_I810;
>> +
>> +	if (errata_i810) {
>> +		ai = omap3_dpll_autoidle_read(clk);
>> +		if (ai) {
>> +			omap3_dpll_deny_idle(clk);
>> +
>> +			/* OCP barrier */
>> +			omap3_dpll_autoidle_read(clk);
>> +		}
>> +	}
>
> Should we just do this unconditionally? It seems like disabling the
> autoidle always before reprogramming is a good idea.

Well, that is a few extra register accesses, but given the DPLL 
re-programming is a slow operation it probably does not matter. Let me 
spin a new version of this patch, it will avoid the need for the errata 
flag also.

-Tero