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Fri, 14 Nov 2025 00:33:02 -0800 (PST) X-Google-Smtp-Source: AGHT+IHb6ke1Nr1AEQwuzlva1GyQBZ0Mlu6vW13cRreQFxUZ2Hgfofqhff7ISlUppU0oCKqca78PRg== X-Received: by 2002:a05:6a00:2d27:b0:776:19f6:5d3d with SMTP id d2e1a72fcca58-7ba39b3ea79mr1552851b3a.2.1763109182293; Fri, 14 Nov 2025 00:33:02 -0800 (PST) Received: from [10.217.216.168] ([202.46.22.19]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7b924aed60bsm4530728b3a.4.2025.11.14.00.32.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Nov 2025 00:33:01 -0800 (PST) Message-ID: <5dcd735d-31bf-4c7f-bf12-89a5cae0d628@oss.qualcomm.com> Date: Fri, 14 Nov 2025 14:02:55 +0530 Precedence: bulk X-Mailing-List: linux-mmc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V1] mmc: sdhci-msm: Avoid early clock doubling during HS400 transition To: Bjorn Andersson Cc: Adrian Hunter , Ulf Hansson , linux-mmc@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, quic_nguyenb@quicinc.com, quic_rampraka@quicinc.com, quic_pragalla@quicinc.com, quic_sayalil@quicinc.com, quic_nitirawa@quicinc.com, quic_bhaskarv@quicinc.com, kernel@oss.qualcomm.com References: <20251110063801.641866-1-sarthak.garg@oss.qualcomm.com> Content-Language: en-US From: Sarthak Garg In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=L+AQguT8 c=1 sm=1 tr=0 ts=6916e940 cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=fChuTYTh2wq5r3m49p7fHw==:17 a=IkcTkHD0fZMA:10 a=6UeiqGixMTsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=EUspDBNiAAAA:8 a=_Uc-8ieBvFDwtx1LFMkA:9 a=QEXdDO2ut3YA:10 a=zc0IvFSfCIW2DFIPzwfm:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTE0MDA2NiBTYWx0ZWRfXzX3K8QJGs0QP 0arj826Pccri+Q8UZQQYjashi6s+5j9QwNVK7v51mxVnGaiOOP5A/xGoxrtTc9HutlC8Hcr4KRM KlYTVk1QR/BrduyXvmQo/1XAatKf4c6a7d5LF7i2KVZ2SmsRIaAQg9HzKVbMkGrSBB05knqkIEP /WF7waKYCMRpPj+4tNztwBF04ryKtDMkz2mZEx6uanWyaahEHV0Yf/dXjJvZszfAeHIOhQcRcFz Bh8OYRGuv6AhEqnKmcefwnU/MTDYa4h4Kj+ad3AN6B1dun46zirPtR3ajRk7yPzWNSOIrzf8S1S RALldsLJro42qEkLisTZY7I0YfgLwy85bUXlf9l/tsyKmZ+J3GAn47rYqAMiL3iPYjPXdLcHS23 kFMcAxRy6a8y7w+XzwbPFJq2Be72Aw== X-Proofpoint-ORIG-GUID: CvRRruEWDKK5ZFRsRlKOTnBdnN7LtK3q X-Proofpoint-GUID: CvRRruEWDKK5ZFRsRlKOTnBdnN7LtK3q X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-14_02,2025-11-13_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 phishscore=0 impostorscore=0 priorityscore=1501 adultscore=0 clxscore=1015 bulkscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2510240001 definitions=main-2511140066 On 11/10/2025 8:09 PM, Bjorn Andersson wrote: > On Mon, Nov 10, 2025 at 12:08:01PM +0530, Sarthak Garg wrote: >> According to the hardware programming guide, the clock frequency must >> remain below 52MHz during the transition to HS400 mode. >> >> However,in the current implementation, the timing is set to HS400 (a >> DDR mode) before adjusting the clock. This causes the clock to double >> prematurely to 104MHz during the transition phase, violating the >> specification and potentially resulting in CRC errors or CMD timeouts. >> >> This change ensures that clock doubling is avoided during intermediate >> transitions and is applied only when the card requires a 200MHz clock >> for HS400 operation. >> >> Signed-off-by: Sarthak Garg >> --- >> drivers/mmc/host/sdhci-msm.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c >> index 4e5edbf2fc9b..eca6a09a4547 100644 >> --- a/drivers/mmc/host/sdhci-msm.c >> +++ b/drivers/mmc/host/sdhci-msm.c >> @@ -355,7 +355,8 @@ static unsigned int msm_get_clock_mult_for_bus_mode(struct sdhci_host *host) >> */ >> if (ios.timing == MMC_TIMING_UHS_DDR50 || >> ios.timing == MMC_TIMING_MMC_DDR52 || >> - ios.timing == MMC_TIMING_MMC_HS400 || >> + (ios.timing == MMC_TIMING_MMC_HS400 && >> + ios.clock == MMC_HS200_MAX_DTR) || > It's a bit ugly that sdhci_msm_execute_tuning() passes ios.clock as an > argument to msm_set_clock_rate_for_bus_mode(), which then calls > msm_get_clock_mult_for_bus_mode() where you reach back into ios.clock. > > In fact, having msm_get_clock_mult_for_bus_mode() reach into > host->mmc->ios to get ios.timing, seems a violation of the original > intent of the prototype. > > > How about cleaning this up and passing "timing" as an argument to > msm_set_clock_rate_for_bus_mode(), and then pass host, clock, and timing > to msm_get_clock_mult_for_bus_mode()? > > That way we avoid this mix of passing parameters to the functions in > both arguments and in state at the same time. > > Regards, > Bjorn Sure will update in V2. Regards, Sarthak >> host->flags & SDHCI_HS400_TUNING) >> return 2; >> return 1; >> -- >> 2.34.1 >> >>