From: Ulf Hansson <ulf.hansson@linaro.org>
To: Siarhei Volkau <lis8215@gmail.com>
Cc: Paul Cercueil <paul@crapouillou.net>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
linux-mips@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org
Subject: Re: [PATCH 1/2] mmc: jz4740: Don't change parent clock rate for some SoCs
Date: Fri, 18 Nov 2022 09:45:48 +0100 [thread overview]
Message-ID: <CAPDyKFrMqCL1-faBadVP3xB-5qiCYsyRUuOHbFZuOWfLdCXwig@mail.gmail.com> (raw)
In-Reply-To: <20221108045300.2084671-2-lis8215@gmail.com>
On Tue, 8 Nov 2022 at 05:53, Siarhei Volkau <lis8215@gmail.com> wrote:
>
> Some SoCs have one clock divider for all MMC units, thus changing one
> affects others as well. This leads to random hangs and memory
> corruptions, observed on the JZ4755 based device with two MMC slots
> used at the same time.
Urgh, that sounds like broken HW to me.
The MMC blocks could share a parent clock (that would need a fixed
rate for it to be applied), assuming there is a separate gate/divider
available per block. But there isn't'?
>
> List of SoCs affected includes: JZ4725b, JZ4755, JZ4760 and JZ4760b.
> However, the MMC driver doesn't distinguish JZ4760 and JZ4770
> which shall remain its behavior. For the JZ4755 is sufficient to
> use JZ4725b's binding. JZ4750 is outside of the patch.
>
> The MMC core has its own clock divisor, rather coarse but suitable well,
> and it shall keep the role of tuning clock for the MMC host in that
> case.
The mmc core doesn't have a clock divisor, but it does control the bus
clock frequency through the ->set_ios() host ops. It needs to do that,
to be able to conform to the (e)MMC, SD and SDIO specifications.
Can you please try to elaborate on the above, so I can better
understand your point?
>
> Signed-off-by: Siarhei Volkau <lis8215@gmail.com>
Kind regards
Uffe
> ---
> drivers/mmc/host/jz4740_mmc.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/jz4740_mmc.c b/drivers/mmc/host/jz4740_mmc.c
> index dc2db9c18..d390ff31d 100644
> --- a/drivers/mmc/host/jz4740_mmc.c
> +++ b/drivers/mmc/host/jz4740_mmc.c
> @@ -114,6 +114,7 @@ enum jz4740_mmc_version {
> JZ_MMC_JZ4740,
> JZ_MMC_JZ4725B,
> JZ_MMC_JZ4760,
> + JZ_MMC_JZ4770,
> JZ_MMC_JZ4780,
> JZ_MMC_X1000,
> };
> @@ -887,7 +888,13 @@ static int jz4740_mmc_set_clock_rate(struct jz4740_mmc_host *host, int rate)
> int real_rate;
>
> jz4740_mmc_clock_disable(host);
> - clk_set_rate(host->clk, host->mmc->f_max);
> +
> + /*
> + * Changing rate on these SoCs affects other MMC units too.
> + * Make sure the rate is configured properly by the CGU driver.
> + */
> + if (host->version != JZ_MMC_JZ4725B && host->version != JZ_MMC_JZ4760)
> + clk_set_rate(host->clk, host->mmc->f_max);
>
> real_rate = clk_get_rate(host->clk);
>
> @@ -992,6 +999,7 @@ static const struct of_device_id jz4740_mmc_of_match[] = {
> { .compatible = "ingenic,jz4740-mmc", .data = (void *) JZ_MMC_JZ4740 },
> { .compatible = "ingenic,jz4725b-mmc", .data = (void *)JZ_MMC_JZ4725B },
> { .compatible = "ingenic,jz4760-mmc", .data = (void *) JZ_MMC_JZ4760 },
> + { .compatible = "ingenic,jz4770-mmc", .data = (void *) JZ_MMC_JZ4770 },
> { .compatible = "ingenic,jz4775-mmc", .data = (void *) JZ_MMC_JZ4780 },
> { .compatible = "ingenic,jz4780-mmc", .data = (void *) JZ_MMC_JZ4780 },
> { .compatible = "ingenic,x1000-mmc", .data = (void *) JZ_MMC_X1000 },
> --
> 2.36.1
>
next prev parent reply other threads:[~2022-11-18 8:47 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 4:52 [PATCH 0/2] mmc: jz4740: Don't change parent clock rate for some SoCs Siarhei Volkau
2022-11-08 4:52 ` [PATCH 1/2] " Siarhei Volkau
2022-11-18 8:45 ` Ulf Hansson [this message]
2022-11-18 9:27 ` Paul Cercueil
2022-11-18 9:51 ` Siarhei Volkau
2022-11-18 10:06 ` Ulf Hansson
2022-11-18 12:48 ` Siarhei Volkau
2022-11-18 13:04 ` Paul Cercueil
2022-11-18 13:14 ` Paul Cercueil
2022-11-18 14:18 ` Aidan MacDonald
2022-11-08 4:53 ` [PATCH 2/2] MIPS: ingenic: rs90: set MMC_MUX clock Siarhei Volkau
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