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Fri, 15 Oct 2021 01:07:15 -0700 Received: from [10.12.67.94] (10.10.115.15) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.2176.14 via Frontend Transport; Fri, 15 Oct 2021 01:07:13 -0700 Subject: Re: [PATCH v5 13/15] clk: at91: sama7g5: remove prescaler part of master clock To: Claudiu Beznea , , , , CC: , , References: <20211011112719.3951784-1-claudiu.beznea@microchip.com> <20211011112719.3951784-14-claudiu.beznea@microchip.com> From: Nicolas Ferre Organization: microchip Message-ID: <9ba33681-f65d-1b65-22ef-85ef973b723a@microchip.com> Date: Fri, 15 Oct 2021 10:07:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20211011112719.3951784-14-claudiu.beznea@microchip.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211015_010716_814612_F1AA5D6A X-CRM114-Status: GOOD ( 19.09 ) 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: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 11/10/2021 at 13:27, Claudiu Beznea wrote: > On SAMA7G5 the prescaler part of master clock has been implemented as a > changeable one. Everytime the prescaler is changed the PMC_SR.MCKRDY bit > must be polled. Value 1 for PMC_SR.MCKRDY means the prescaler update is > done. Driver polls for this bit until it becomes 1. On SAMA7G5 it has > been discovered that in some conditions the PMC_SR.MCKRDY is not rising > but the rate it provides it's stable. The workaround is to add a timeout > when polling for PMC_SR.MCKRDY. At the moment, for SAMA7G5, the prescaler > will be removed from Linux clock tree as all the frequencies for CPU could > be obtained from PLL and also there will be less overhead when changing > frequency via DVFS. > > Signed-off-by: Claudiu Beznea Indeed: Acked-by: Nicolas Ferre > --- > drivers/clk/at91/sama7g5.c | 11 +---------- > 1 file changed, 1 insertion(+), 10 deletions(-) > > diff --git a/drivers/clk/at91/sama7g5.c b/drivers/clk/at91/sama7g5.c > index c66bde6f7b47..fd9d17eabf54 100644 > --- a/drivers/clk/at91/sama7g5.c > +++ b/drivers/clk/at91/sama7g5.c > @@ -992,16 +992,7 @@ static void __init sama7g5_pmc_setup(struct device_node *np) > } > > parent_names[0] = "cpupll_divpmcck"; > - hw = at91_clk_register_master_pres(regmap, "cpuck", 1, parent_names, > - &mck0_layout, &mck0_characteristics, > - &pmc_mck0_lock, > - CLK_SET_RATE_PARENT, 0); > - if (IS_ERR(hw)) > - goto err_free; > - > - sama7g5_pmc->chws[PMC_CPU] = hw; > - > - hw = at91_clk_register_master_div(regmap, "mck0", "cpuck", > + hw = at91_clk_register_master_div(regmap, "mck0", "cpupll_divpmcck", > &mck0_layout, &mck0_characteristics, > &pmc_mck0_lock, CLK_GET_RATE_NOCACHE, 5); > if (IS_ERR(hw)) > -- Nicolas Ferre _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel