* [PATCH v3] mmc: sdhci: fix minimum clock rate for v3 controller
@ 2020-01-15 9:54 Michał Mirosław
2020-01-15 10:01 ` Adrian Hunter
2020-01-16 14:39 ` Ulf Hansson
0 siblings, 2 replies; 3+ messages in thread
From: Michał Mirosław @ 2020-01-15 9:54 UTC (permalink / raw)
To: Adrian Hunter, Ulf Hansson; +Cc: linux-mmc, linux-kernel
For SDHCIv3+ with programmable clock mode, minimal clock frequency is
still base clock / max(divider). Minimal programmable clock frequency is
always greater than minimal divided clock frequency. Without this patch,
SDHCI uses out-of-spec initial frequency when multiplier is big enough:
mmc1: mmc_rescan_try_freq: trying to init card at 468750 Hz
[for 480 MHz source clock divided by 1024]
The code in sdhci_calc_clk() already chooses a correct SDCLK clock mode.
Cc: stable@vger.kernel.org
Fixes: c3ed3877625f ("mmc: sdhci: add support for programmable clock mode")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
---
v3: commitmsg/comment rewording
v2: extend commitmsg and add comment
---
drivers/mmc/host/sdhci.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 96609c961465..24fb6d710de6 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -3903,11 +3903,13 @@ int sdhci_setup_host(struct sdhci_host *host)
if (host->ops->get_min_clock)
mmc->f_min = host->ops->get_min_clock(host);
else if (host->version >= SDHCI_SPEC_300) {
- if (host->clk_mul) {
- mmc->f_min = (host->max_clk * host->clk_mul) / 1024;
+ if (host->clk_mul)
max_clk = host->max_clk * host->clk_mul;
- } else
- mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
+ /*
+ * Divided Clock Mode minimum clock rate is always less than
+ * Programmable Clock Mode minimum clock rate.
+ */
+ mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
} else
mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_200;
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] mmc: sdhci: fix minimum clock rate for v3 controller
2020-01-15 9:54 [PATCH v3] mmc: sdhci: fix minimum clock rate for v3 controller Michał Mirosław
@ 2020-01-15 10:01 ` Adrian Hunter
2020-01-16 14:39 ` Ulf Hansson
1 sibling, 0 replies; 3+ messages in thread
From: Adrian Hunter @ 2020-01-15 10:01 UTC (permalink / raw)
To: Michał Mirosław, Ulf Hansson; +Cc: linux-mmc, linux-kernel
On 15/01/20 11:54 am, Michał Mirosław wrote:
> For SDHCIv3+ with programmable clock mode, minimal clock frequency is
> still base clock / max(divider). Minimal programmable clock frequency is
> always greater than minimal divided clock frequency. Without this patch,
> SDHCI uses out-of-spec initial frequency when multiplier is big enough:
>
> mmc1: mmc_rescan_try_freq: trying to init card at 468750 Hz
> [for 480 MHz source clock divided by 1024]
>
> The code in sdhci_calc_clk() already chooses a correct SDCLK clock mode.
>
> Cc: stable@vger.kernel.org
> Fixes: c3ed3877625f ("mmc: sdhci: add support for programmable clock mode")
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> v3: commitmsg/comment rewording
> v2: extend commitmsg and add comment
> ---
> drivers/mmc/host/sdhci.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 96609c961465..24fb6d710de6 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3903,11 +3903,13 @@ int sdhci_setup_host(struct sdhci_host *host)
> if (host->ops->get_min_clock)
> mmc->f_min = host->ops->get_min_clock(host);
> else if (host->version >= SDHCI_SPEC_300) {
> - if (host->clk_mul) {
> - mmc->f_min = (host->max_clk * host->clk_mul) / 1024;
> + if (host->clk_mul)
> max_clk = host->max_clk * host->clk_mul;
> - } else
> - mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
> + /*
> + * Divided Clock Mode minimum clock rate is always less than
> + * Programmable Clock Mode minimum clock rate.
> + */
> + mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
> } else
> mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_200;
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] mmc: sdhci: fix minimum clock rate for v3 controller
2020-01-15 9:54 [PATCH v3] mmc: sdhci: fix minimum clock rate for v3 controller Michał Mirosław
2020-01-15 10:01 ` Adrian Hunter
@ 2020-01-16 14:39 ` Ulf Hansson
1 sibling, 0 replies; 3+ messages in thread
From: Ulf Hansson @ 2020-01-16 14:39 UTC (permalink / raw)
To: Michał Mirosław
Cc: Adrian Hunter, linux-mmc, Linux Kernel Mailing List
On Wed, 15 Jan 2020 at 10:54, Michał Mirosław <mirq-linux@rere.qmqm.pl> wrote:
>
> For SDHCIv3+ with programmable clock mode, minimal clock frequency is
> still base clock / max(divider). Minimal programmable clock frequency is
> always greater than minimal divided clock frequency. Without this patch,
> SDHCI uses out-of-spec initial frequency when multiplier is big enough:
>
> mmc1: mmc_rescan_try_freq: trying to init card at 468750 Hz
> [for 480 MHz source clock divided by 1024]
>
> The code in sdhci_calc_clk() already chooses a correct SDCLK clock mode.
>
> Cc: stable@vger.kernel.org
> Fixes: c3ed3877625f ("mmc: sdhci: add support for programmable clock mode")
> Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Applied for fixes, thanks!
Kind regards
Uffe
> ---
> v3: commitmsg/comment rewording
> v2: extend commitmsg and add comment
> ---
> drivers/mmc/host/sdhci.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 96609c961465..24fb6d710de6 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3903,11 +3903,13 @@ int sdhci_setup_host(struct sdhci_host *host)
> if (host->ops->get_min_clock)
> mmc->f_min = host->ops->get_min_clock(host);
> else if (host->version >= SDHCI_SPEC_300) {
> - if (host->clk_mul) {
> - mmc->f_min = (host->max_clk * host->clk_mul) / 1024;
> + if (host->clk_mul)
> max_clk = host->max_clk * host->clk_mul;
> - } else
> - mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
> + /*
> + * Divided Clock Mode minimum clock rate is always less than
> + * Programmable Clock Mode minimum clock rate.
> + */
> + mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_300;
> } else
> mmc->f_min = host->max_clk / SDHCI_MAX_DIV_SPEC_200;
>
> --
> 2.20.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-01-16 14:40 UTC | newest]
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2020-01-15 9:54 [PATCH v3] mmc: sdhci: fix minimum clock rate for v3 controller Michał Mirosław
2020-01-15 10:01 ` Adrian Hunter
2020-01-16 14:39 ` Ulf Hansson
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