linux-kernel - [PATCH] mmc: core: limit probe clock frequency to configured f

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Date:   Thu, 02 Jan 2020 11:54:58 +0100
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     linux-mmc@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>, linux-kernel@...r.kernel.org
Subject: [PATCH] mmc: core: limit probe clock frequency to configured f_max

Currently MMC core disregards host->f_max during card initialization
phase. Obey upper boundary for the clock frequency and skip faster
speeds when they are above the limit.

Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
---
 drivers/mmc/core/core.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index abf8f5eb0a1c..aa54d359dab7 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2330,7 +2330,13 @@ void mmc_rescan(struct work_struct *work)
 	}
 
 	for (i = 0; i < ARRAY_SIZE(freqs); i++) {
-		if (!mmc_rescan_try_freq(host, max(freqs[i], host->f_min)))
+		unsigned int freq = freqs[i];
+		if (freq > host->f_max) {
+			if (i + 1 < ARRAY_SIZE(freqs))
+				continue;
+			freq = host->f_max;
+		}
+		if (!mmc_rescan_try_freq(host, max(freq, host->f_min)))
 			break;
 		if (freqs[i] <= host->f_min)
 			break;
@@ -2344,7 +2350,7 @@ void mmc_rescan(struct work_struct *work)
 
 void mmc_start_host(struct mmc_host *host)
 {
-	host->f_init = max(freqs[0], host->f_min);
+	host->f_init = max(min(freqs[0], host->f_max), host->f_min);
 	host->rescan_disable = 0;
 	host->ios.power_mode = MMC_POWER_UNDEFINED;
 
-- 
2.20.1